Welcome to the next tutorial of our Raspberry Pi programming course. Our previous tutorial looked at how to Interface DS18B20 with Raspberry Pi 4. This tutorial will teach us how to create a time-lapse video with still images and understand how phototimer and FFmpeg work.
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | Raspberry Pi 4 | Amazon | Buy Now | |
When photographing something over a lengthy period, "time-lapse" comes to mind. A video can be created by mixing the still photos. Plant development may be tracked with time-lapse movies, as can the changing of the seasons. They can also be utilized as low-resolution security cameras.
Cameras that can be used with the Raspberry Pi are a bit limited. A powered USB hub is required for most webcams that are compatible. For this post, we’ll be using a camera specifically made for the Raspberry Pi. The camera module can be plugged into a specified port on the Raspberry Pi. How to do it;
Shutting down the pi is recommended before adding a camera. A power button should be installed on Pi 4 so that you may shut down the device safely every time.
Slide the cord into the port by using an image as a guide. Finally, press down tabs, securing the cable to the motherboard.
Click on the main menu button, select Preferences, and then click Pi Configuration if you're using a monitor. Enable the camera by clicking on the Interfaces tab.
To continue, headless users must type the command below. Make sure the camera is turned on in Interfacing Options. Rebooting the Raspberry Pi will be required.
Individual stills are used to create time-lapse videos. We'll be using raspistill to acquire our time-lapse images. As part of the Raspberry Pi OS, you don't need to install anything extra. The are two way to record a time lapse:
Raspistill is a Linux-based software library that aims to make it easier for Linux users to use sophisticated camera systems. We can use open-source programs running on ARM processors to control the camera system with the Raspberry Pi. Almost all of the Broadcom GPU's proprietary code is bypassed, which customers have no access to.
It provides a C++ API to apps and operates at the base of configuring a camera and enabling the program to obtain image frames. Image buffers are stored in memory space and can be supplied to either video encoders (like H.264) or still image encoding algorithms like JPEG or PNG. raspistill, on the other hand, does not perform any image encoding or display operations directly.
An illustration of how to take time-lapse photography is shown in the following image.
In this case, the time-lapse capture was 10 seconds long. The Raspberry will wait for a total of 2000 milliseconds between each image. For 10 seconds, the Raspberry Pi will take a picture every two seconds.
The photos will be stored as .jpg files. This example uses the name "Pic" and a number that increases with each frame to identify each image. The final digit of percent 04d is a zero. Pic0000.jpg and Pic0001.jpg would be the names of the first two photographs, and so on. Change this value according to the requirements of your project.
Your time-lapse video needs to be put together once all of your photographs have been taken. FFmpeg is the tool we'll be utilizing to generate our timelapse video. The command to download the package is as follows:
Allow the installation to be complete before moving on. Using this command, you can create a finished video:
Pic%04d.jpg corresponds to the image filename you specified in the preceding section. If you have previously changed this name, please do so here. With the -r option, you can specify how many frames per second you want to record. When creating a time-lapse video, replace the phrase video-file with your name. Make sure to keep the .mp4 file extension.
A high-speed audio and video conversion tool that can also capture from a webcast source is included. On the fly, video resizing and sampling can also be done with high-grade polyphase filters.
A plain output URL specifies an indefinite number of outputs that FFmpeg can read from (standard files, piped streams, network streams, capturing devices, etc.), whereas the -i option specifies the number of input files. An output URL is encountered on the command-line interface that cannot be treated as an option.
Video/audio/subtitle/attachment/data streams can all be included in a single input or output URL. The container format may limit the quantity or type of stream used. The -map option can map input streams to output streams, either automatically or manually.
For options, input files must be referred to by their indices (0-based). It's not uncommon to have an infinite number of input files. Indexes are used to identify streams inside a file. As an illustration, the encoding 2:3 designates the third input file's fourth and final stream. In addition, check out the chapter on Stream specifiers.
A Python library named phototimer will be used to control the raspistill command-line that comes pre-installed on the Raspbian OS.
Using docker, you can develop, analyze, and publish apps in a short time. To run phototimer with Python installed, you'll need to use Docker with Raspbian Lite.
A new location does not necessitate an SSH login. The lapse of time will be restarted.
Download the Docker image, activate the camera interface, and start the container instead of executing a git clone on each device.
If you disconnect from the container, docker will keep track of the log information and will enable you to reconnect at any time.
We can easily set up docker with the following set of commands.
Download the docker file as a zip as shown below
Or use the terminal by copying the phototimer code as shown here:
If git isn't already installed, use the following command to add it:
By modifying the config.py file, you can change the time-appearance lapses and duration.
You will likely want to alter the default time-lapse settings so that they better fit your requirements, which start at 4 am and end at 8 pm.
For some reason, overall quality of 35/100 produces a substantially smaller image than one with a quality of 60-80/100. You can modify the file to determine how much space you'll need.
Depending on how your camera is positioned, the image may need to be flipped horizontally or vertically. True or False in each situation will have the same result.
To achieve a specific aspect ratio, you can change the height or width of the image in this way. The default setting is what I use.
The Docker container must be re-built and restarted every time you change your setup.
When docker does a build, it will construct an image from the current directory's code and a base image, like Debian.
The most crucial part is that the image we create right now contains everything our application might want.
For those just getting started, these are some helpful keyboard shortcuts and CLI commands:
The default time zone for the Docker container is UTC. If you're in a different time zone, you'll want to adjust your daylight savings time accordingly.
Docker can be configured to run in your current local time by adding the following additional option to the command:
As a result, the following is what a time-lapse in Texas, United States, might look like:
Below are some time-lapse images taken from the raspberry pi camera.
To save your photos to your laptop, follow these steps once you've captured a few pictures:
The ssh and SCP functions are included in Git for Windows, which may be installed on Windows.
You'll need a way to connect to your new rig when you're not near your wi-fi router if you plan on doing the same thing I did. There are a few ideas to get you started:
All Pi models allow networking via USB, and it is very straightforward to establish and will not interfere with the wi-fi network. You will have to bring a USB cord to each new site to directly change the Wireless SSID/password on the pi.
Plugging an SD card into your computer while on the road allows you to update your wi-fi configuration file easily, provided there is an SD card adapter nearby. The existing configuration will be replaced with this new one on the next reboot.
If you're comfortable with Linux, you can use hostapd to create your hotspot on the RPi. To connect to your Raspberry Pi, you'll need a computer with an Ethernet cable and a web browser.
Install your wi-fi Username and password and use that to start/stop timelapse capture and download files if you won't be using the rig outside your location.
The imported files should be in the correct order if you drag them onto the timeline after they've been imported, so be sure to do that. The crop factor should be set to "fill." Instead of 4.0 seconds, use 0.1 seconds for the showtime every frame.
It is often necessary to transfer documents between the Linux laptop to an industrial Raspberry Pi for testing purposes.
Occasionally, you'll need to transfer files or folders between your commercial Raspberry to your computer.
There is no longer a need for you to worry about transmitting files via email, pen drive, or any other method that takes up time. Automation and industry control can help you automate the process in this post.
As the name suggests, SCP refers to secure copy. This command-line application lets you securely transfer files and folders between two remote places, such as between your local computer and another computer or between your computer and another computer.
You may see SCP info by using the command below:
Using SCP, you can transfer files to the RPi in the quickest possible manner. There is a learning curve associated with this strategy for novice users, but you'll be glad you did once you get the hang of it.
You must activate ssh on your Raspberry Pi to use SCP.
A free program like Giphy can help you convert the videos to a GIF; however, this will lower the number of frames.
We learned how to use the Raspberry Pi to create a time-lapse animation in this lesson. In addition, we looked into the pi camera raspistill interface and used FFmpeg and phototimer to create a time-lapse. We also learnt how to interface our raspberry pi with our pc using ssh and transfer files between the two computers. The following tutorial will teach how to design and code a GPIO soundboard using raspberry pi 4.
This is the third tutorial in our Raspberry Pi programming course. In the previous chapter, we learned how to install Raspbian on our Raspberry Pi mini-computer. In this chapter, we'll learn how to use a VNC server to remotely control and see its desktop from our computer.
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | Raspberry Pi 4 | Amazon | Buy Now | |
Computing over a network is known as "virtual network computing," or "VNC." To remotely control another computer, you can use this screen-sharing technology, which works on all major operating systems. As a result, a remote user can interact with a computer's display (screen, keyboard, and mouse) as if they were sitting right in front of it.
VNC takes advantage of the client/server concept. Rather than installing a VNC server on the distant device, users will instead use a VNC viewer or client on the device they wish to control. Use a tablet or a smartphone in place of one of the previously mentioned computers. As soon as a viewer and a server are connected, the server gives the viewer a screen copy of the computer on the other side of the world.
Thanks to the application, both the remote user and the connected user can see and control everything on the distant computer's screen using keyboard and mouse instructions from afar.
Other programs (referred to as "clients") can access the resources on a computer server. The server can provide services to one or more clients, such as data or resource sharing, in what is known as the "client-server model." The advantage of this strategy is that a single server can service many clients, while a single client can make use of several servers. A server will respond to a request from a client by sending back a response.
When a computer has VNC Server software installed, it can be accessed and controlled remotely from another device. The software makes it possible to stream the device's desktop to another computer running VNC Viewer. Once a connection is established, users using VNC Viewer can view exactly what a person seated in front of the remote computer sees (with permission).
A viewer is a piece of software that allows you to see the contents of a digital file in its entirety.
Remote control of local PCs and mobile devices is made possible through the usage of VNC Viewer. Using VNC Viewer software, a user can access and operate a machine from another place using a device such as a computer, tablet, or smartphone.
As a desktop sharing system, it delivers keystrokes, mouse clicks, and other input events to a remote computer running VNC Server so that you may control it from your mobile device once connected. It's as if you're sitting directly in front of the computer that you've accessed remotely.
VNC uses a protocol called remote framebuffer to share data between the client and server, which determines the type of data exchanged. Using this, clients can access and control another machine from afar. Because it's compatible with all windowing apps and systems, it may be used on any mainstream operating system, including Windows, macOS, Linux, and others.
User access to a computer's monitor, mouse and keyboard is provided via the RFB client or viewer (also known as a client). Framebuffer updates originate on the RFB server (as in the windowing system). A key goal of Remote Framebuffer is to run on a wide range of hardware and to simplify the process of building a client by requiring as little input from the client as possible.
File transmission, more advanced compression, and stricter security procedures have all been added to RFB since its inception as a basic protocol. When using VNC, clients and servers can agree on the appropriate RFB version to use, as well as the security and compression options that are supported by both parties. Cross-platform interoperability is made possible as a result of this.
There are times when you won't be able to use your Raspberry Pi. For instance, you might have forgotten about your Raspberry Pi while away, or it may be buried beneath your TV or other devices. Using Raspbian and the free VNC software, you can connect to your Raspberry Pi wirelessly from any other device running Raspbian. You have the option of connecting to the internet or to your home network.
Begin by ensuring that both computers involved are on the same local network.
Select Preferences > Raspberry Pi Configuration from the apps menu icon (raspberry) at the top-left of the screen.
The default password for Raspbian is 'raspberry,' which you should change right away. By clicking the Change Password option, you can set a new password. Select the Enabled radio button next to VNC on the Interfaces tab. OK when you're finished. Menu bar in upper right corner of screen has VNC button at end of menu bar VNC Server will be launched as soon as you click on it.
Note your Ip address for the next steps.
You can now link your Raspberry Pi to another computer. Instead of a Windows computer, you might use a Mac or Linux computer on the same network or even another Raspberry Pi.
With a web-based interface, VNC Viewer may be used on a variety of platforms including macOS, Linux, Android, and iOS. On the official website of realvnc, download VNC Viewer. To use the software, it must first be downloaded and then installed.
In the "Enter a VNC Server address or search" box of the VNC Viewer, enter the Raspberry Pi's IP address (the four numbers displayed in VNC Server). RETURN is all that is needed to disconnect when a connection is established. If an error message appears, press the Enter key to proceed.
For security reasons, you'll need to log in with your Raspberry Pi's username and password. To remember your password and access Raspbian, select ‘Forgot Password’ and then OK.
The Raspberry Pi window is shown on your windows computer. By dragging the mouse cursor around the screen, you can see the Raspberry Pi's mouse. Remote control of your Raspberry Pi is now possible thanks to this window.
When you hover your mouse over the top of the VNC Viewer window, a menu will appear. Enter The Full Screen option is located to the left of the Options and allows you to have the preview window take over your screen. Because your Raspberry Pi display may not be compatible with your PC display, choose Scale from the menu (such that it is set to Scale Automatically).
Your Raspberry Pi will provide you a desktop PC-like experience.
Close the VNC preview window and use the VNC Connect menu bar to get to the properties. You can end a session from the drop-down menu.
To access your Raspberry Pi's desktop, simply open VNC Viewer from the Address Book. To reopen the connection, simply double-click on the icon and select Properties from the context menu that appears.
Enter 'Raspberry Pi' in the Name field. This will give your screen a more personal touch. After that, select Options. Automatic is the default setting for Picture Quality on your camera. The lower the setting, the better; if you have a fast connection, the higher it should be.
Make sure to check out the "Experts" section at the bottom. In this section, you'll find configuration options for pretty about everything on your computer. You can change the False to True option in the Fullscreen drop down box. In VNC Viewer, you can preview your Raspberry Pi in full-screen mode. After you've made your options, click OK to keep them.
You may access your Raspberry Pi from anywhere in the world with a RealVNC account.
Verify your identity in the upper left corner of VNC Viewer when it has been opened. Sign up if you don’t have an account. Set up a password for your account. Keep your password at least eight characters long and difficult to decipher. There is a RealVNC home page that you will be taken to. Verify your email address and you're done setting up.
A single account must now be used to sign in to both of these applications.
You should be able to see the VNC Viewer Sign In window from the computer. Your Raspberry Pi must be running VNC Server before you can connect to the cloud.
Go back to the VNC Viewer application on your PC. In the Address Book area, you will find a Raspberry Pi Window, but you'll also notice a Team option immediately below it.
This account can be used from different networks and operates remotely.
Sending and receiving files is possible between the Pi and computer. We've created a new text file called test.txt in our Documents folder.
Connect to the Pi using VNC Viewer to send a file. An option to transfer files can be found in the VNC Viewer preview window's menu.
Sending files is as simple as clicking the Send Files button in the VNC Viewer's File Transfer window and the transfer will begin. Click Open after you've selected a file from your computer's file picker. On your Raspberry Pi's desktop, the file will be saved. The message "Download complete" will appear in the File Transfer window; close it.
With VNC Viewer, it is possible to download files from your Raspberry Pi's SD card. VNC Server icon can be found in the Raspbian menu bar by right-clicking it. Select File Transfer from the VNC Server drop-down option to open the File Transfer window.
Your Raspberry Pi can now be accessed remotely. The screen and keyboard can now be removed from your Raspberry Pi and left connected to the network. The PC connection will be waiting for you when you're ready.
Using your smartphone, you can also remotely connect to the Raspberry Pi. Download the VNC Viewer software from the app store, then, open your VNC Connect account and log in using your email address and password.
Your Raspberry Pi will be listed in the Team drop-down menu. Click it and input your Raspberry Pi's username and password.
On start up, you will have to go through the 'Control the computer' step. The 'How to control' window will open once you click Next. This screen shows you how to use movements like mouse clicks on the touchscreen. Start using Raspberry Pi from your phone by closing this window.
To move the cursor, make use of your smartphone's touchscreen. An on-screen keyboard can be accessed with a simple swipe of your finger on a key at the top of the app.
Even on your phone, you can now access your Raspberry Pi. Remote monitoring has never been easier.
When it comes to deploying new software and systems, there will always be some trepidation, and there is a lot of misinformation floating about that influences how people feel about doing so. However, this has the drawback of preventing individuals and organizations from reaping the full benefits of new technologies.
In this article, we'll debunk some of the most popular myths regarding VNC Connect, many of which can be traced back to VNC's open-source roots.
Because buying two keyboards, monitors, and mice for your computer and Raspberry Pi would be prohibitively expensive, VNC is a great option to gain access to your raspberry pi remotely. The two computers can be used at the same time, and you don't have to switch between them. So far, we've learned how to set up our mini-computer for VNC and how to establish a remote connection to the VNC viewer. Our first project will be to use Python to control the GPIO pins of a Raspberry Pi 4, which we will cover in the next topic.
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | Raspberry Pi 4 | Amazon | Buy Now | |
The next step is to make sure you have your board and SD card. The Raspberry Pi has an operating system because it is a full computer. For those who prefer a GUI desktop experience, a headless mode is still an option. Most people use Raspbian, a Debian-based operating system tailored specifically for the Raspberry Pi. However, there are other options. An excellent starting point is this operating system, which is likely to support other Linux packages that you are already familiar with.
Other means to install and run an operating system on the Raspberry Pi are also available. The imager installer is the most convenient method. As long as you're familiar with the operating system ISO, you may download it to your SD card, format your SD card and mount the ISO, and then boot the Pi. Follow the imager installation option if that's all gibberish to you.
For this process, we will open our browser and navigate to the raspberry pi website and down to the software option, you will see a download for windows. This button allows you to download the imager for windows which in my case I am using. If you are using another operating system like mac and ubuntu there are also imagers for those particular operating systems.
The executable imager file will be downloaded to your computer as seen below.
This software allows us to flash our operating system into the micro-SD card which will be used in the mini-computer.
Connect the card reader with an sd card in it to your computer through USB or a regular card slot.
On your computer, navigate to the location you downloaded the imager software and run it. In windows just double-click on it and it should startup.
On the pi imager window, there are two options and when we click the choose storage, our SD card is detected since we plugged it into our pc.
If you have any other drive plugged into your pc, they will also appear on the window therefore be careful to select the right one otherwise you will override the wrong drive and lose your saved files.
We will click on the other button "choose os" that is on the pi imager window to select the operating system we want to flash into our SD card. You will see different types of operating systems available for installation and we will go ahead and select the 32-bit raspberry pi os.
Once all the required parameters are set, i.e., the os and storage, go ahead and click the write button. The flashing process begins and it takes a minimum of 5 minutes to complete.
NOOBS (New Out of the Box Software) is an automated installer provided by the Pi Foundation, but for this article, we're going to forego it for now.
To complete numerous projects, it is a good idea for you to learn about "flashing" the SD card yourself. Despite NOOBS's reputation as a beginner's tool, I found this one to be easier to use.
You'll need an image file and an application to put it to your SD card to install an operating system. However, you can use any operating system of your choice for this guide. For example LibreELEC for a media box; RetroPie for retro gaming; and so on.
Because it's accessible for Windows, macOS, and Linux, Etcher is my go-to tool for writing to the SD card. There may be partitions that aren't visible in Windows, but these may be cleaned out with diskpart if you've previously used the SD card in a Pi.)
The full Raspbian image with suggested software is what I'm running, so go ahead and download it if that's what your Pi model calls for. It will either be an IMG file or an IMG compressed into a ZIP file (which you don't have to do if you're using Etcher).
It's as simple as opening Etcher and clicking the Select Image button to select your downloaded file. Flash your SD card by selecting it as the target. Selecting a destination drive should only be done with extreme caution, as the operation will wipe whatever disk you select.
Once the SD card has been ejected, you can insert it into your Pi, connect the HDMI wire to a display or TV, and turn on the Pi by plugging it into the wall. Once you've landed on the Raspbian desktop, you can begin fiddling with your Wi-Fi and software installations with apt.
Now that flashing is complete, with the pi powered off, we will go ahead and eject the storage SD from the pc and put it back to the raspberry pi SD slot. Then we will go ahead and plug the power cord back in and our mini computer should start. If you mouse, keyboard and screen go ahead in the previous tutorial and see how they are connected since they are necessary for this step.
The mini-computer boots up into the os and you will find a window with instructions on what to do. Follow through the graphical user interface, provide a password, location, screen, and Wi-Fi connection.
Then go ahead and install updates and the raspberry pi will reboot. A couple of issues will be solved when it boots up such as window dimensions and resolution.
We will do some more configurations in the terminal, therefore go ahead and start the terminal.
Preferences on the menu can be found in the Configuration tool, which enables you to change most of your Pi's settings, including the password.
Several options are available, as illustrated in the screenshots below. We'll enable vnc and ssh for the time being. The Raspberry Pi's fundamental system settings can be modified in this area.
It's a good idea to change the factory default "raspberry" password for the pi user. When your Raspberry Pi boots up, choose between using Desktop or CLI (command line interface), and enable Auto Login.
You can set your Raspberry Pi to wait until a network connection is available before starting up, by selecting network at boot.
You can choose whether or not your Raspberry Pi boots up with a splash screen.
There are numerous ways to connect your Raspberry Pi to other devices and components. For your Raspberry Pi to recognize that a specific type of connection has been made to it, you must use the Interfaces tab to enable or disable the various connections.
To use the camera on the Raspberry Pi, you must first enable it.
A Raspberry Pi can be accessed remotely through SSH or VNC.
To enable the SPI, I2C, and Serial (Rx, Tx) GPIO pins, go to the SPI menu. To enable the 1-Wire GPIO pins, go to the 1-Wire menu. To enable the 1-Wire GPIO pin, go to the 1-Wire menu. To enable Remote GPIO, go to the Remote GPIO menu.
We can alter the performance settings of our Raspberry Pi on this tab if we need to do so for any specific project.
Caution: Changing the performance parameters on your Raspberry Pi could cause it to behave strangely or stop working altogether.
If you want to boost your computer's performance, you can overclock the CPU and adjust its voltage.
This enables you to customize your Raspberry Pi's settings based on where you live.
To configure your Raspberry Pi's locale, select the language, nation, and character set you want to use.
For example, you may want to change your time zone, or you may want to switch to a different type of keyboard layout.
Go ahead and finalize the configuration and reboot now that you've completed the setup.
You don't need much more than a remote desktop program and the IP address of your Raspberry Pi to get started.
Open Remote Desktop Connection on your Windows computer to get started. The app will appear as seen in the image below.
In the "Computer:" field, type in the local IP address of your Raspberry Pi (1.), and then click the "Connect" button (2.).
Enter the account's "username" and "password" from your Raspberry Pi.
If you're logging in as the default pi user, your username and password should be "pi" and "raspberry," respectively.
Have trouble connecting to the Raspberry Pi? Double-check that your IP address is accurate. TeamViewer or TightVNC are two other options.
I hope you can now access the Raspberry Pi's remote desktop using the tool of your choice.
Python will be installed on your Raspberry Pi, and you'll see how simple it is to do so. This can be accomplished in a few simple steps thanks to Python's default package repository.
Thonny, a Python IDE, is pre-installed on desktop versions of Raspberry Pi OS. It is much easier, faster, and more pleasant to write code when using an IDE. Open Thonny on your Raspberry Pi, and then learn a little bit of Python in the process.
The toolbar is located at the very top of the screen. All the buttons you'll ever need to work with the editor are right here. The "Save" and "Run" buttons are the only ones you'll need (1.)
It's time for the center box. All of your Python code can be written here. (2.)
Finally, the Python shell is at the bottom. You can use this to directly communicate with Python. The output of your code can also be found here (3.).
You should now have a better understanding of how to get started with Python on your Raspberry Pi. This instruction explains how to install the Raspbian operating system, configure its interface, and install the Python interpreter with a few basic command lines. On the Raspberry Pi, we also demonstrated how to start a Python code editor to develop code.
to our new beginner’s course on Raspberry Pi. This course is appropriate for anyone using either a traditional Raspberry Pi board or the new Raspberry Pi 400 board that includes an integrated keyboard and display. Learning how to code, building robots, and doing plenty of other strange and exciting things are all possible with this low-cost computer setup. The Raspberry Pi can do everything a computer can do, from surfing the web to viewing movies and music, and playing video games.
Raspberry Pi is much more than a modern computer. It`s created to educate young people on how to program in languages such as Scratch and Python, and it comes with all of the major programming languages pre-installed. The world is in desperate need of programmers now more than ever, and Raspberry Pi has sparked a new generation's interest in computer science and technology. Raspberry Pi is used by people of all ages to build intriguing projects ranging from old-school gaming systems to internet-connected weather equipment.
| Where To Buy? | ||||
|---|---|---|---|---|
| No. | Components | Distributor | Link To Buy | |
| 1 | Raspberry Pi 4 | Amazon | Buy Now | |
In this course, we'll learn how to make games, build robots, or hack all kinds of fantastic projects. The Raspberry Pi 4 Model B will be covered in this course. In the event that you're working with a different model of Raspberry Pi, don't be worried. whatever is taught here can be applied to any other model in the family.
It is a small computer about the size of a credit card that can run the Linux operating system. It uses a "system on a chip," which combines the CPU, GPU, RAM, USB ports, and other components into a single chip.
To distinguish it from traditional computers that conceal their internal components behind a casing, the Raspberry Pi's ports and functions are fully exposed, a protective case is available to buy. If you want to know how different computer components work and where to put the various peripherals, this is a great resource.
All Raspberry Pi models share one feature in common:
Now you've got a little machine that runs a lot of free software, so that's good. Exactly what can you do with it? Fortunately, I've got a simple and fun Python project that I used to teach middle school children in a coding lesson.
The Raspberry Pi features a number of parts that can be used to control the Raspberry Pi as well as other devices. The following ports will be available on your Raspberry Pi:
The majority of the Raspberry Pi's system resides on an integrated circuit, which is what the term "system-on-chip" refers to. Included in this is the CPU, which is referred to as a computer's 'brain,' as well as the graphics processing unit (GPU).
A brain is useless without memory, therefore you'll notice another chip to the side of the SoC, tiny and black plastic, like a cube where RAM is located. When you're working on a Raspberry Pi, the RAM stores your work; it's only when you save it to the microSD card that it's written to the microSD card. The volatile and non-volatile memories of the Raspberry Pi are made up of these components. When the Raspberry Pi is turned off, the volatile RAM loses its contents, however, the non-volatile microSD card retains them.
A metallic lid covers the Raspberry Pi's radio component, which allows it to communicate wirelessly with other devices. In actuality, the radio has two main functions. Wi-Fi and Bluetooth are built-in, so you can use them to communicate with your computer and other nearby smart devices, sensors or cellphones.
Just behind the middle row of USB ports, an additional black, plastic-covered chip is seen towards the board's bottom border. The USB controller manages the four USB ports. The network controller is positioned next to this chip. An integrated circuit (PMIC) is also located on the upper left side of this board. It is in charge of converting power from a USB port to the precise voltage that the Raspberry Pi needs.
The circuit board contains a variety of ports, beginning with four ports in the right side of the bottom edge. You can connect any USB-compatible device to your Raspberry Pi using these ports, including keyboards, mice, digital cameras, and flash drives. One of the two types of USB ports is a USB 2.0 port, which uses version two of the USB standard; the other is a USB 3.0 port, which uses version three.
There is an Ethernet port. Using an RJ45 cable, a Raspberry Pi can be linked with a wired computer network via this port. You'll notice two LEDs at the bottom, which indicate the connection is operational.
There is a 3.5 mm audio-visual jack. Connecting to amplified speakers rather than headphone jacks improves sound quality, but the headphone jack can still be used. Audio and video signals can be transmitted using the TRRS (tip-ring-ring-sleeve) adapter, which connects the 3.5 mm AV jack with projectors, tv, and other displays that can receive composite video signals.
The camera serial interface (CSI), or camera connector, as it is most commonly called, is located above the AV jack and has a strange-looking plastic flap that may be pulled up (CSI). This allows you to connect a camera, which you'll learn later in this course.
There are two micro HDMI connections available, which are a scaled-down version of the connectors seen on gaming consoles, set-top boxes, and televisions. Multimedia denotes that it can transport both audio and video information, and high-definition indicates that the quality will be excellent. A computer monitor, television, or projector will be needed to connect the Raspberry Pi to these adapters.
The port above the HDMI ports is where you'll plug in the Raspberry Pi's power supply. USB Type-C ports can be found on smartphones, tablets, and other mobile devices. Instead of a standard mobile charger, employ the certified Raspberry Pi USB Type-C Power Supply for the best results.
There is a strange-looking connector at the top of the board, which appears to be the camera connector at first sight, but it's not. It is for usage with a Raspberry Pi Touch Display.
In two rows of 20 pins each, you'll find 40 metal pins along the right edge of the board. To communicate with peripherals such as LEDs and buttons to temperature sensors, joysticks, and pulse rate monitors, the Raspberry Pi includes a function known as GPIO (general-purpose input/output).
The Raspberry Pi has one more port, the micro-SD connector, which is on the other side of the circuit board. The MicroSD card is inserted here and you'll find all the files you've saved and installed as well as the operating system that makes your Raspberry Pi work.
Unfortunately, the Raspberry Pi lacks the ability to run either Macintosh or Windows. Instead, it uses Raspbian, a Linux distribution. Installing Raspbian on your own micro-SD card is also possible using the NOOBS installation. You'll see this loading screen when you insert in the microSD card with Raspbian installed and turn on the Raspberry Pi.
As you've seen, the desktop on your huge PC looks exactly like the one you are used to. A web browser, terminal, picture viewer, calculator, and a slew of other tools are all included by default.
The Raspberry Pi is the heart of your project, but without a power supply or storage, it won't be able to go very far. To get started, you'll need the following:
The power supply standard for the Raspberry Pi 4 has been upgraded from microUSB to USB-C, which is an improvement. Powering your Raspberry Pi is best done with a dedicated power adapter from the Raspberry Pi Foundation.
The later Pi models use microSD cards instead of the normal SD cards that were used in the original Pi models A and B. However, not all SD cards function correctly, therefore it's preferable to acquire a pre-loaded operating system with the original Raspberry Pi microSD card or a tested suitable card, such as the SanDisk Ultra 32GB.
This is technically optional, but we strongly advise it. It is a good idea to use a case to protect your bare board rather than leaving it exposed. The FLIRC case has a built-in heatsink, making it an excellent choice for older models of the Raspberry Pi.
You can control your Raspberry Pi using a keyboard and a mouse. Raspberry Pi can utilize almost any USB-connected keyboard and mouse, wired or wireless. However, don`t use 'gaming' keyboards with flashing lights since they consume too much power to be used successfully.
USB gamepads are also necessary when you are building consoles like a gaming rig, therefore, don't forget about them.
We are now going to set up our minicomputer therefore follow these simple steps to get yours up and running:
Congratulations! You've successfully assembled your Raspberry Pi! I hope you have something like this:
At this point in the course, we've learned about the Raspberry Pi computer and what each component does. Our minicomputer has now been set up, and in the next tutorial, we'll learn how to use the python programming language with the Raspbian operating system.
Welcome to the next lesson of our python programming class. In the last session, we looked at the use of If-else statements and created simple programs to demonstrate the concept. While loops are another type of conditional statement, and in this tutorial, we'll look at how they're used.
In this article, you'll learn how to prematurely exit a while loop, a Python control structure for endless iteration. You will also learn how to write conditions in a single line to produce short and readable code.
The term "iteration" refers to the practice of repeatedly running the same piece of code. A loop is a type of programming structure that implements iteration.
Both indefinite and definite iterations are recognized as valid programming constructs. Infinite iteration doesn't specify how many times the loop will be executed. As long as a condition is met, the chosen block will be executed again. An iteration that uses a definite iteration specifies how many times it will run the selected block.
While Loops are used to iterate over the same code block for an unlimited couple of iterations until a condition is met.
While Loops are used to repeat the same code block indefinitely until a condition is met, if a given Boolean condition is completed at the end of the block, the "do while" loop will continue to run a provided block of code, or it will not.
Only one statement is required for the Do While Loop to terminate. However, the While loop may terminate with no statements executed, while the While loop may terminate with statements executed.
This type of control flow statement specifies iteration, allowing the code to be executed again and again. When we know how many times we want to run a code section, a for loop comes in handy.
Here, we'll explore how the Python while statement can be used to build loops. We'll begin with a simple design and gradually add to it.
Listed below is a basic while loop's structure:
Block denotes an execution block that will be repeated over and over again. As with an if statement, this is indicated by indentation.
Indentation is used to define blocks in all Python control structures. See the previous tutorial on grouping statements for a refresher.
In the controlling expression, expr, variables are initialized and updated during the loop's execution.
In this case, the expr parameter is evaluated first in a Boolean context. If this is true, then the loop's body is run. The body is executed when the expression returns to true. The program moves to the topmost statement following the loop body if the condition in expr is false.
Take a look at the following loop:
This is what we're seeing in this case. n starts as five. The loop body is run because n > 0 is true. n is greater than 0. Line 3 of the loop body prints the value of n after decreasing by 1 to 4 places.
The expression is re-evaluated from the top of the loop after the loop's body has completed. Because it's still true, the code in the body runs once again, printing 3 on the screen.
It goes on like this until n equals zero. That is when the expression is tested, and the loop is broken. The program would typically restart execution from the top most statement following the loop's body, but there isn't one here.
It's worth noting that the controlling expression of the while loop is tested first. If the loop body is false at the start, it will never be executed:
Because of this, n is set to zero when the loop is encountered. There is no need for the loop body because the controlling statement n > 0 is false.
Below is another while loop that doesn't use the numeric comparison:
Lists evaluated in a Boolean context are either truthy or false, depending on whether or not they contain elements. As long as there are elements in it, a is true. The loop terminates when the list is empty and all items have been deleted using the pop () method.
The whole body of the while loop is executed each time it is executed. Python has two keywords, break and continue, to prevent a loop from repeating itself.
This statement breaks a loop completely and immediately in Python. Python performs the next statement in the program after the loop body, which ends the current loop iteration. As soon as an expression is evaluated, it is evaluated again to see if the loop will continue or end.
The following diagram illustrates the difference between the statements "break" and "continue":
Break.py is a Python script that demonstrates the use of the 'break' statement:
Using a command-line interpreter to run break.py yields the following results:
The break code is executed when n reaches the value of 2.0. Execution immediately moves to the print () call on line 7 after complete termination of the loop.
A continue statement replaces the break in the next script, continue.py.
The output is something like this:
When n is 2, the loop is terminated by the continue statement. Thus, the number 2 is omitted. The condition is re-evaluated at the top of the loop, and it is still true. As before, the loop terminates when n equals 0.
While loops in Python can have an optional else condition at the end. Unlike most other programming languages, Python has this unique functionality. Syntax in the form of a diagram:
The other clause's further statements will execute when the while loop completes, as shown in this example.
You may be wondering, "How is that useful?" at this point. After the while loop, you could insert the following statements directly after it:
Additional statements will be run regardless of whether or not the while loop is terminated.
An else condition will only execute if the loop stops "by exhaustion"—that is until the controlling condition is false; otherwise, no subsequent statements will be executed. If a break statement is used to break the loop, the else condition is not executed.
Think about the following scenario:
Variable n becomes 0, and therefore n > 0 became false. The loop's block runs until the condition is exhausted. The else clause is executed since the loop is allowed to run its course.
Consider the following example to see the difference:
The else condition is not executed because the loop is prematurely interrupted by the break.
The term else may appear to have a different meaning in the while loop then it does in the if statement. In order to make it more understandable, you may try one of the following:
You are free to disregard either of these interpretations if you don't find them helpful.
If you need to find a certain item on a list, this is a common scenario. If the item is discovered, you can use the break to leave the loop. Also, else condition can contain code to be run if the item is not found:
Assume you've written an infinite while loop. This may sound weird, right?
As an illustration, consider the following:
Ctrl+C, a keyboard interrupt, was used to end this code. There was no way this could have ended. The vertical ellipsis represented in this output has taken the place of several output lines that were omitted.
We're all going to be in a lot of trouble if True can ever be false. On the other hand, False creates an infinite loop that might conceivably run indefinitely.
However, this is a typical pattern, and it may not sound like something you would want to do. Code for a service that accepts service requests and operates indefinitely is a good example. In this situation, "forever" implies until you turn it off or the universe reaches the point of no return.
Alternatively, keep in mind that the break statement can be used to exit a loop. Instead of evaluating a condition at the top, conditions recognized within the loop body may make it easier to terminate the loop.
If you'd rather, you can use pop () to delete each item in the list in turn, as illustrated above:
Not a is true when a is empty, and the break statement terminates the loop.
Multiple break statements can be specified in a loop:
Breaking out of the loop at various points rather than trying to define every possible termination condition in the loop header is often preferable in situations like this.
Infinite loops can be convenient in some circumstances. It's important to remember that the loop must be stopped sometimes, or it will become limitless.
Generally, it is possible to nest Python control structures inside one another. Nested conditional statements, for example, are possible: if/elif/else.
The following code shows how a while loop can be nested inside of another while loop:
Nested loops are affected by statements like "break" or "continue" since they are nested within each other.
Loops can be nested in and out of the if/elif/else statements and the other way around.
All Python control structures can be mixed and matched to your heart's content. That is precisely how it should be. You can only nest while loops a maximum of four deep, which would be unpleasant if there were unforeseen constraints like these: 'A while loop cannot be embedded within an if statement.' Trying to recall them all would be nearly impossible.
Poor programming language design is evidenced by the presence of seemingly random numerical or logical constraints. Python, fortunately, does not have any.
You can specify a while loop in the same way you do an if statement: on a single line. If the loop body has many statements, semicolons (;) can be used to divide them:
To be clear, this technique only works with simple declarative. Compound statements cannot be combined in a single line. As a result, you can write an if statement on the same line as a while loop:
You can also do this:
Note that PEP 8 forbids the use of numerous assertions on a single line. "Since this is a bad idea anyway, you generally shouldn't do it too often.
The Python while loop was used in this tutorial to demonstrate indefinite iteration. You can now create sophisticated and straightforward while loops, thanks to the knowledge you've gained thus far. The else clause can be used in conjunction with a while loop to handle endless loops. If you've followed along, you should understand how to run the same code repeatedly. The next lesson will cover iteration with for loops with an explicit limit on the number of iterations.
Welcome to the fifteenth chapter of this python course. Python lists and tuples were studied extensively in the last session, and we learned how to manipulate the data contained in these types of structures. You've only experienced sequential execution up to this point, where each statement is performed sequentially in the order they appear in the code.
However, the real world is frequently more nuanced. Sometimes, a program must skip over certain statements, run a set of statements repetitively, or pick between other sets of statements to execute. This is called "conditional branching."
That's when control structures come into play, which controls the sequence in which statements in a program are executed.
The if statement is the first control structure you'll encounter in Python.
Real-world situations frequently need us to examine the information around us and then make a decision based on what we've observed. As an illustration;
Unless it's raining, I'll be mowing the yard. It's correct to say that if it's pouring or snowing, I won't be mowing the lawn.
This type of decision-making is performed in Python programs using the if statement. If an expression has a certain value, and that value is known, a statement or set of statements can be executed.
Let`s get started.
We'll begin with the simplest form of an if statement. This is how it appears in its most basic form:
As you can see:
Execution of the statement occurs when the expression evaluates to a "truthy" value. No action takes place if expr is false. You must include a colon (:) after expr. Python does not require the parentheses around expr, as some other programming languages do.
This type of if statement is used in a variety of ways:
There is no effect on pressing Enter key after you have typed the print('yes') expression when using these examples interactively in a REPL session. There are multiple lines in this command. You must press Enter a second time to complete it. Executing a script file doesn't necessitate the use of an extra newline.
Suppose, on the other hand, that you wish to assess a condition and then take many actions if it is true:
There is only one 'statement' in each of the cases above, as demonstrated. It's necessary to be able to express "Do this if [expr] is true."
Syntactic devices, which bring together several statements into a single compound statement or block, are the most common technique employed by most programming languages. Syntactically, a block is considered to be a single entity. Explanation: All statements in the block are performed when it is an "if" target and "expr" is true. None of them are true if expr is false.
It is possible to define blocks in virtually all programming languages, however, this is not always possible. Let's have a look at Python's approach.
You may have heard the offside rule in football, right? Well, in programming, the off-side rule is a tenet of the Python programming language. Indentation is used by rule-abiding languages to define blocks. Off-side rule adherent Python is one of few languages.
Indentation has a specific meaning in a Python program, as you learned in the last tutorial on the structure of Python programs. The reason for this is that indentation is used to denote blocks of related statements. A block in a Python program consists of a series of statements that are all indented the same way. Thus, a Python compound if statement looks like this:
Lines 2 to 5 are considered to be part of the same block because they all have the same indentation level. If expr is true, the entire block executes, while if expr is false, the block is skipped. Following the following statement> (line 6) execution continues.
Tokens are not used to indicate the end of a block. There are two ways to tell when a block has come to a close.
Take foo.py as an example:
This is what happens when you run foo.py:
Lines 2-5 have the same indentation and print () commands. As a result, they form the code that would be executed if the underlying assumption was correct. Because it is untrue, the entire block is ignored. It doesn't matter whether or not lines 2 to 5 are executed, the first statement with a lower indentation level, the print () statement on line 6, is executed.
There is no limit on how deep blocks can be nested. Each new block is defined by a new indent, and each previous block is ended by an outdent. In the end, the structure is simple to follow, consistent, and easy to understand.
This script, called blocks.py, is a bit more complicated.
The following is an example of what you'll see after running this script:
When entering multiline expressions into a REPL session, you must include an extra newline because of the off-side constraint. Otherwise, the translator would have no means of knowing the if block's final statement had been entered.
Perhaps you'd like to know what other options are out there. It's unclear how blocks are declared in languages that don't follow the off-side rule
To denote the beginning and end of a block in most programming languages, special tokens are used as a strategy. Curly braces () are used to define blocks in Perl, for example:
Other programming languages, such as C/C++ and Java, also make use of curly brackets in this fashion.
Algol and Pascal, on the other hand, employ the keywords begin and end to denote the beginning and finish of a block.
It's all about how you look at it. They tend to have a strong opinion about how they do things in general. The off-side rule can generate a lot of controversies when it comes up for discussion.
The off-side rule is an issue you'll have to deal with if you are writing Python code. Python's control structures all rely on it, and you'll see this in several upcoming lectures. Many programmers initially resisted Python's approach to defining blocks, but they've since learned to enjoy it and even prefer it over more traditional methods.
If a certain condition is met, you may wish to conduct a certain course of action, but if it isn't, you may want to specify another course of action. The else clause is used to accomplish this:
If expr> is true, the first suite is run and the second is skipped. Second Suite Execution Is Skipped If 'Expr' Is False Execution resumes after the second suite is completed. Indentation is used to distinguish between the two suites, as indicated in the preceding paragraph. For example, lines 4 to 5 are run, and lines 7 to 8 are omitted because x is less than 50:
Because x exceeds 50 in this case, the first suite is omitted in favor of the second, which is run.
It's also possible to branch execution based on a variety of possible outcomes. One or more elif clauses can be used to do this. Each expr is evaluated in turn by Python, which then executes the set of instructions associated with the first one that is found to be true.
You can provide as many elif clauses as you like. The else clause is not required. One must be provided at the end if it is present:
An if statement with elif clauses, like the ‘and’ and ‘or’ operators, uses short-circuit evaluation. The remaining expressions are not tested when one of the tests returns true and its block is run. This can be seen in the following example:
There is a zero division in the second equation, and an undefined variable var is referred to in the third. As long as the first criterion is met, neither option will be assessed.
The following is a standard way to write if (expr) indented on a separate line from the statement (statement):
However, an entire if statement can be written on a single line. The following is essentially the same as the previous example. Semicolons are used to separate multiple statements on the same line.
One exception to this rule is when an entire if statement is written in one line. Functionally, this is just like the example above. Separated by semicolons, you can have multiple statements on a single line.
Unlike the other if statement forms, this one does not control the flow of program execution, unlike the ones listed above. It's more like an expression-defining operator. Conditional expr> is first evaluated in the above example. The expression evaluates to expr1 if it is true. It returns a value of expr2 if it is false.
It's important to note that the evaluation of the middle expression comes before the evaluation of the two ends, and as a result, only one of the two ends is returned. Here are a few real-world examples to illustrate my point:
Selective assignment of variables is a popular application of the conditional statement. Let's say you're trying to figure out which of two numbers is greater. You could, of course, use the built-in method max() to accomplish the same thing. But what if you want to start from scratch and develop your code?
The term "code stub" refers to a placeholder for a section of code that hasn't yet been implemented, such as when writing a test case.
Token delimiters, such as the curly brackets in C or Perl, can be used to define a code stub in these languages. Perl or C code like the following is acceptable:
The curly braces here denote an empty area. Even if the expression x is true, Perl or C will do nothing after evaluating it.
Specifying an empty block is impossible because Python utilizes indentation rather than delimiters. A follow-up statement, either indented or on the same line, is required after an if statement that begins with if expr. Consider foo.py as an example:
Foo.py doesn't work if it is attempted to be run.
This issue can be solved with the Python pass command. It does not affect the program's behavior. With this placeholder, the interpreter is kept happy in situations where a statement is required syntactically but no action is desired:
Foo.py is now error-free:
Congratulations! You have completed this tutorial on conditional statements in Python. We've explored the if-else statement in Python code and learned how to organize statements into blocks and understand the control structure concept in Python. Developing more complicated Python programs relies heavily on understanding these ideas. The while statement and the for statement are two new control structures that will be introduced in the next tutorial.
Welcome to the fourteenth chapter of our python tutorial course. In the last lesson, we looked at sets and operations done to sets, including union and intersection. In this tutorial, we'll take a closer look at lists and tuples to see how they're used. Python's most versatile and useful data types are lists and tuples. A non-trivial Python application will nearly always have these.
Lists and tuples have a number of significant features that you'll learn about. In this course, you'll understand the definitions and applications of these terms. By the time you're done, you'll know when and how to employ different Python object kinds.
In other words, Lists are similar to arrays in many other programming languages because they allow you to store any number of arbitrary elements within them. For a list to exist in Python, an object sequence must be enclosed in square brackets ([]) as seen in the example below:
In other words, a list is more than a collection of things. Collections of things are organized in this way. Lists are defined by the order in which their elements are listed, and this order is maintained throughout the life of the list itself. For more information on Python data types, check the dictionaries tutorial (coming soon).
A comparison of two lists that contain the same contents but are organized differently is impossible:
A list can be made up of any number of items. A list can have all of its elements of the same type:
Different kinds of elements can be used.
Complex objects such as functions, classes, and modules can also reside in lists, as you'll see in forthcoming tutorials:
From 0 to the limit of your computer's RAM, a list can contain any number of items.
Uniqueness isn't required for list objects. There is no limit to the number of times an object can be listed:
This is a question you could ask yourself whenever you need to access items in a list, and the answer is yes: an index in square brackets can be used to access items in a list. In other words, it's the same as looking up individual characters in a string. As with strings, the indexing of lists is zero-based. The following is a sample list:
Here are the indices for the items in a:
Slicing is another option. For lists, the formula a[m:n] retrieves only the part of a that is between m and but not containing n in the list a.
As you learned before, an item in a list can be of any type. Another list is included in that. You can have as many sublists as you want within a single list.
As an illustration, consider the following (obviously fabricated) scenario:
x refers to an item structure depicted in the image below:
These three strings below, are all one character in length:
Example of sublists are shown below:
Simply add an additional index to have access to the items in a sublist:
To the degree that your computer's RAM allows, there is no limit to the depth or complexity of nested lists in this manner.
A lot of your experience so far has been with atomic data types. Primitive units, such as integers and floats, are those that cannot be decomposed further. Once they've been allocated, these types aren't able to be modified. Changing the value of an integer doesn't make sense at all. If you prefer a different integer, simply change the one you've assigned.
The string type, on the other hand, is a complex type. Strings can be broken down into their constituent characters. Think of a string of characters and how they might be rearranged. However, this is not possible. Strings are also immutable in Python.
This is the first time you've met a mutable data type, the list. It is possible to add or remove items from a list at any time after it has been created. Lists can be modified in a variety of ways in Python.
A single value can be replaced in a list using indexing and simple assignment.
A string can't be used to accomplish this, as demonstrated in the Python tutorial Strings and Character Data.
In order to remove a list item, use the del command:
Suppose you'd like to change several neighboring items in a list at the same time. The following Python syntax for a slice assignment makes this possible.
Consider an iterable list at this point. iterable is substituted for the slice of a specified here:
It's not necessary to have the same number of new elements as the number of old ones. Python simply increases or decreases the list based on the task at hand. Utilize a slice which only refers to one element when you wish to replace a single element with multiple ones:
You can also add items to a list without having to remove anything from the original list. Simply type [n:n] to produce a zero-length slice at the requested index.
You can remove a large number of items from a list by assigning the correct slice to an empty list. It is possible to use the del statement with the same slice:
To add more items to the beginning or end of a list, you can use the + concatenation operator or the += augmented assignment operator:
For example, a singleton list can only have one item in it, hence, it must be added to a different list:
Python provides a number of built-in methods for modifying lists. Below, you'll find more information on these methods. The target string was not directly modified in the previous tutorial's string methods. Strings are immutable, so this is why. String methods, on the other hand, give you back a completely rewritten string object. They don't change the target string at all:
List methods differ from other approaches. Lists are changeable, therefore the target list gets modified while the list method is running.
Adds a new item to the end of a collection.
List functions change the target list on the fly. They don't give you a new one:
Adds items from an iterable to a list.
Yes, it's most likely what you're expecting. Additionally, an iterable is required as an argument to extend(). iterable> elements are inserted one at a time:
To put it another way, extend() functions similarly to the plus sign (+). Because it alters the list while it's still in place, it's equivalent to the += operator:
A new element is added to a collection with the help of this method. Object obj> is inserted into the list an at the index indicated by insert(index>, obj>). It's a[index>] obj, and the remaining list items are moved rightward after the function call.
In a list, this function removes one item. remove(<obj>) list an is cleared of obj. An exception is thrown if obj> is not in a:
In a list, this function removes one item. There are two key differences between this method and remove():
The last item in the list is simply removed by calling pop():
Specifying an index in the optional index parameter causes this command to remove and return the given item. Like string and list indexing, index can be negative.
Python lists are described in this course by a set of six qualities. Finally, lists can be reordered. Sections above have shown many instances of this. A list expands as new things are added:
Similarly, as things are removed from a list, the list gets smaller.
A tuple is a collection of things that are arranged in a specific order. When it comes to the pronunciation of a word or phrase, it depends on who you ask. A few people say it as if it were spelled "too-ple," while others pronounce it as "tup-ple," which rhymes with "supple." Because everyone I know pronounces "supple," "quintuple," "sextuple," and "octuple" as though they rhyme with "supple," my preference is for the latter.
Lists and tuples are nearly identical, with the exception of the following characteristics:
As an illustration of tuples in action, consider the following code sample:
There's no need to worry! Reversing a tuple is as simple as using our usual string and list reversal process:
It's important to remember that although though tuples are constructed using parenthesis, you still use square brackets to index and slice them.
A tuple is a list with the same properties as a list: it's ordered, it can include arbitrary objects; it's indexable and sliceable; and it can be nestable like any other list. However, they cannot be changed:
There is a way to display the values of several objects at once in a Python REPL session by simply inserting them one after the other between commas:
Because Python interprets the input as a tuple, it presents the response in parentheses. The definition of a tuple has a peculiarity that you should know about. It's impossible to be vague when creating a tuple that has no items or a tuple with two or more. A tuple is defined in Python:
Because parentheses are used to denote operator precedence in expressions, the expression (2) creates an int object. Before closing parentheses, you need to put in an extra comma (,): This tells Python that you plan to create a single tuple.
There has to be a mechanism to define a singleton tuple, even if you don't need to do it very often.
Using Python, you can display a singleton tuple by putting a comma in front of it:
You've seen this before: a literal tuple can be allocated to a single object.
When this happens, it's as if the tuple's contents have been "stuffed" into the object:
"packed" objects can be "unpacked" into a new tuple by assigning them to the new tuple's objects.
Otherwise, a problem will emerge when unpacking a tuple: if there are more variables than values, an error will occur.
Compound assignments can be created by combining the steps of packing and unpacking into a single expression.
It's important to remember that in this tuple, the components on the left and right must be equal.
It is possible to leave off the parentheses required to denote a tuple in Python assignments like this one and a few others:
If you're unsure whether or not the parentheses are necessary, go ahead and put them in if you have any doubt. Python idioms are made possible by multiple assignment. As a programmer, it is common to have two variables whose values must be swapped. While the swap is taking place, a temporary variable must be used to store one of the values.
In Python, a simple tuple assignment is all that is needed to perform a swap:
If you have ever used a Python temporary variable to exchange values, this is the pinnacle of modern technology. It's the greatest it's ever going to be.
Congratulations! You have now completed the list and tuple tutorial. Python lists and tuples were introduced, along with some of their basic features and operations. In Python, you'll be relying on these all the time. It is a list's primary property that it is organized. It is impossible to modify the order of a list's elements, unless, of course, the list is altered. The same is true for tuples, except that they can't be updated. Python's conditional statements will be covered in the upcoming lesson.
This is the next lesson in our Python course. Previously, we looked at an overview of the different data types in python such as dictionaries, Boolean and sets. This tutorial will focus on Python sets to get a deeper understanding of this data type, so let's get started. During your schooling, there is a good chance you learned about sets and set theory. Venn diagrams may even be familiar to you:
Don't worry if you don't recognize this! You should still be able to access this tutorial without any problems. Rigidly defining a set in mathematics can be both abstract and difficult to understand. A set is thought of as a well-defined group of unique objects, which are sometimes called "elements."
Python's built-in set type facilitates the grouping of items into sets, which is important in programming as well. Unique actions that can be done on a set separate it from other object types.
Using Python, you learn how to create set objects and learn about the various activities they can be used for. We've covered lists and dictionaries in previous tutorials, so you should be familiar with when a set is the right tool for the job. You'll also look at "frozen sets," which are similar to sets but differ in one significant way.
The following features describe the built-in set type in Python:
Let us explore what all that entails, and how you can interact with sets in Python.
Iter> is an iterable (imagine a list or tuple for now) that generates a list of items to be included in the set. This is the same as the list method's iter> argument .extend():
A string can also be supplied to set() because strings are iterable. As you can see, list(s) generates a list of the characters in the string s. In the same way, set(s) generates a set of the characters in s:
The resulting sets are not in any order. The definition's original order isn't always followed. Values that are duplicated such as the string 'foo' in the first two examples and the letter 'u' in the third are only represented in the set once.
Curly braces () can also be used to define a set:
Each obj> becomes a separate element of the set when defined in this way, even if it is iterable. The .append() list technique works similarly. As a result, the sets depicted above can alternatively be described as follows:
To summarize:
Consider the following differences between these two definitions:
A set can be empty. The set() method is the sole way to define an empty set in Python because empty curly braces () are regarded as an empty dictionary.
In Boolean logic, an empty set is false:
A Boolean variable can only have two values in general: True or False. In other words, we call a variable a Boolean variable if it can only have these two values. It's frequently used to denote an expression's Truth value. True equals 1 and False equals 0 in mathematics. In contrast to electronics, a light bulb has a high value (that is 1) when it is switched on, and vice versa.
The len() function, which returns the number of items in a set, can be used to test for membership with the in and not in operators:
Sets are incompatible with many of the operations that operate with other composite python data types. Sets, for instance, cannot be indexed or sliced. Python, on the other hand, provides set object methods that are quite similar to the operations given for mathematical sets.
Most, but not all, set operations in Python can be accomplished using either an operator or a method. Let's look at how set union works as an illustration of how these operators and methods function. With sets, x1, and x2, the union of the two sets yields a set that contains all members from both sets.
Consider the following:
The results of combining x1 and x2 are shown below.
Note that in the union, 'baz,' will appear in both x1 and x2 only once. There are never any duplicate values in a set.
The | operator in Python can be used to execute set union:
The union() method can also be used to get a set union. The method is called using one of the sets as an input, and the other is supplied as a parameter:
The operator and method operate identically when used in the instances above. However, there is a distinction between them. Both operands must be set when using the | operator. In contrast, the union() method takes any iterable as an input, turns it into a set, and then executes the union.
Take note of the differences between the following two statements:
Both try to combine ('baz', 'qux', 'quux') with x1. The | operator fails, but the union() method succeeds.
A list of Python set operations is shown below. Some tasks are accomplished by an operator, while others are completed by a method, and still, others are completed by both. When a set is required, procedures normally accept any iterable as an input, whereas operators require actual sets as operands.
x1 | x2 [| x3 ...]
Add two or more sets together to get the unionset.
x1.union(x2) and x1 | x2: returns the sets of all items in either x1 or x2.
With either the operator or the method, you can specify more than two sets:
All elements that appear in any of the defined sets are included in the final set.
x1 & x2 [& x3 ...]
Calculate the point at where two or more sets intersect.
The set of items shared by both x1 and x2 is returned by x1.intersection(x2) and x1 & x2:
The intersection method and operator, like set union, allow you to specify multiple sets.
Only components that appear in all of the provided sets are included in the resulting set.
Calculate the difference between at least two sets.
Two examples of x1.difference are x1.difference(x2) and x1 - x2 (x2). produce a list of all x1 elements that aren't found in x2:
difference(x2) and x1 - x2 return the set that is returned when any elements in x2 are removed or subtracted from x1.
You can specify multiple sets once more:
The procedure is executed from left to right when several sets are supplied. In the foregoing example, the first step is to compute a - b, which yields 1, 2, 3, 300. After that, the set is taken from c, leaving 1, 2, and 3:
Calculate the difference between two symmetric sets.
The sets containing all items in x1 or x2, but not both, are returned by symmetric difference(x2) and x1 x2:
Additionally, the operator ^ enables for more than two sets:
The operation is executed from left to right once multiple sets are supplied, just like with the difference operator.
Surprisingly, although the operator supports multiple sets, the symmetric_difference() function does not:
Sets can be altered, even though their components need to be immutable types. Similar to the operations above, the contents of a set can be altered using a combination of operators and processes.
Each of the aforementioned operators has an augmented assignment form that can be used to change a set. Each person takes a different approach.
x1 |= x2 [| x3 ...]
The union can be used to change the state of a set.
x1 &= x2 [& x3 ...]
Intersection can be used to change a set.
x1 &= x2 and update(x2) x1 should be updated with only the items that present in both x1 and x2:
x1 -= x2 [| x3 ...]
Make a difference in a set.
x1.difference update(x2) and x1 -= x2 remove components found in x2 from x1:
x1 ^= x2
By using symmetric difference, you can change a set.
x1=x2 and update(x2) update x1, maintaining either x1 or x2 components, but not both:
Aside from the augmented operators listed above, Python has several other ways of modifying sets.
Adds a new element to a collection.
x.add(elem>) appends elem> to x:
Removes one of a set's elements.
elem> is removed from x using x.remove(elem>). If elem> is not in x, Python throws an exception:
Removes one of a set's elements.
elem> is also removed by x.discard(elem>). If elem> is not in x, this procedure does nothing instead of issuing an exception:
A set contains the random element to be removed from it.
x.pop() removes and returns an element from x that is picked at random. x.pop() throws an exception if x is null:
A frozenset is a Python in-built type that is similar to a set but is immutable. The following non-modifying procedures are possible on a frozenset:
Attempts to change a frozenset, on the other hand, fail:
You might suppose that because a frozenset is immutable, it can't be the target of an augmented assignment operator. However, keep the following in mind:
With frozensets in place, Python does not perform augmented assignments. The expression y &= s is practically the same as y = y & s. It makes no changes to the original x. It's associating x with a new item, and the one with which it was previously connected has vanished.
The id() method can be used to check this:
Following the augmented assignment, f has a new integer identification. It has been reassigned rather than changed in situ. When a Python object is the target of an augmented assignment operator, it is updated in place. Frozensets, on the other hand, are not. Frozensets are useful in cases where you need an immutable object yet wish to utilize a set. For example, because set elements must be immutable, a set with items that are also set cannot be defined.:
When you need to define a set of sets, frozensets, which are immutable, are the way to go:
Remember from the previous dictionary instruction that a dictionary key must be immutable. The in-built set type can't be used as a dictionary key for the following reason:
If you're looking for a way to use sets as dictionary keys, try frozensets:
We must use a membership operator to see if an element exists in a set. To check if an element is present in a sequence, membership operators are employed (e.g., strings, lists, tuples, sets, or dictionaries). As mentioned below, there are two membership operators.
Use the len () function to calculate the total number of items in a set. The number of items in an object is returned by this function. The function's input can be any sort of sequence, including a text, dictionary, list, or tuple, in addition to a set.
This tutorial teaches you how to create set objects in Python and how to interact with them using functions, operators, and methods. Python's main built-in data types should now be familiar to you. Then you'll examine the organization and structure of the code of a Python program that interacts with those items. In the next topic we will look at python list and python tuple.
Welcome to the next tutorial of our python course. We learned about python numbers in the last tutorial, and in this tutorial, Data types in Python include, dictionaries, sets, and Boolean, among others. We'll give a quick overview of the above data types in this section but later in this course, we'll go over each of them in-depth.
In the Python programming language, data types are a necessary concept. Python assigns a data type to each value. Data Types are used to classify data objects or to assign a value to a data category. It aids in comprehending the many operations that can be applied to a value.
Python considers everything to be an object. Classes are represented by data types in Python. Variables are the names given to the objects or instances of these classes. Let's look at the various data types that Python has to offer.
Our variables can be used to store values that are of a specific data type. The type of a variable does not need to be specified when declaring a variable in Python because it is dynamically typed. The interpreter's default behavior is to tie a value to its type.
a = 5
We didn't define the type of the variable a, which has the integer value of five. Variable a will be automatically interpreted as an integer by Python.
Python can be used to determine variable`s type in a program. It is possible to retrieve the type of a variable in Python by using the type() method. Consider the following scenario for defining values for various data kinds and determining their type.
Different kinds of values can be stored in a variable. A name of a person, for example, must be stored as a string, while his or her identity number should be stored as an integer. Python comes with a number of standard data types, each of which has its own storage method. The following is a list of the data types defined in Python.
The term "number" refers to a sort of data that contains numerical values. Integer, float, and complex values are all available in the Python Numbers data type. The type() method in Python can be used to determine variable’s data type. isinstance() determines whether an object belongs to a specific class. When a variable is assigned a number, Python produces Number objects.
v = 5
print("type ", type(v))
z = 40.5
print("type", type(z))
t = 1+3j
print("type", type(t))
print(" Is this true or not?:", isinstance(1+3j,complex))
Python can handle three different forms of numeric data.
The list might include a variety of data. A comma (,) is used to divide the elements in the list, which are then enclosed in square brackets []. To access the data of the list, we can use slice [:] operators. The concatenation (+) and repetition (*) operators behave similarly in lists and strings. Consider this scenario.
Output:
[1, 'hello', 'students', 5]
[5]
[1, 'hello']
[1, 'hello', 'students', 5, 1, 'hello', 'students', 5]
[1, 'hello', 'students', 5, 1, 'hello', 'students', 5, 1, 'hello', 'students', 5]
The components of a list can be accessed in a variety of ways.
To get to a specific item in a list, we can use the index operator []. In Python, indices begin at 0 and go up from there. As a result, an index of 0 to 4 will be assigned to a list of five members. If you try to access indexes that aren't listed here, you will recieve an IndexError. An integer must be used as the index. We can't use floats or other kinds because TypeError will occur. Nested indexing is used to access nested listings.
Python sequences can be indexed using negative numbers. For example, the index -1 represents the last item, and the number -2 represents the second-last item.
lists are mutable, meaning their elements can be changed. To update a single item or a set of objects, use the assignment operator (=).
The in-built del function can be used to remove one or more entries from a list. It has the ability to completely remove the list.
In many ways, a tuple is comparable to a list. Tuples are built up of items of several data kinds, similar to lists. The tuple components enclosed in parentheses are separated by a comma (,).
Read-only data structures, such as tuples, do not allow changes to its elements' size or value.
Let's look at a simple tuple example.
tuup = ("hello"students", 5)
# Check tuup type
print (type(tuup ))
#Print tuup
print (tuup )
# Tuup slice
print (tuup[1:])
print (tuup[0:1])
# Tuple concat
print (tuup + tuup)
# Tuup repetition by use of *
print (tuup * 4)
# Addition of a value to the tuup. It throws an error.
t[5] = "hi"
Output:
<class 'tuple'>
('hello', 'students', 5)
('students', 5)
('hello',)
('hello', 'students', 5, 'hello', 'students', 5)
('hello', 'students', 5, 'hello', 'students', 5, 'hello', 'students', 5, 'hello', 'students', 5)
The index operator [] can be used in a tuple to access items, with the index starting at 0.
As a result, a tuple with six elements will have indices ranging from 0 to 5. If you try to access an index that isn't in the tuple index range, you'll get an IndexError (6,7,... in this example).
We can't use floating or other forms of data because the index must be an integer. Because of this, a TypeError is generated.
Using the nested index feature, tuples that have been nested can be found.
Tuples are immutable, unlike lists.
This implies that once a tuple's elements have been assigned, they cannot be changed. It is possible to alter the nested items of an element that is itself a changeable data type, such as a list.
A tuple can also have different values assigned to it (reassignment).
A tuple's elements cannot be changed, as previously stated. We can't delete or remove entries from a tuple because of this.
The keyword del, on the other hand, can be used to completely delete tuples.
A dictionary is a collection of objects that have a key and a value. It's similar to a hash table or an associative array in that each key stores a single value. A primitive data type can be stored in key, but a Python object can be stored in value.
The curly brackets contain the elements in the dictionary, which are separated by a comma (,).
Consider this scenario.
m = {1:'Jim', 2:'malec', 3:'joy', 4:'mark'}
print (m)
print ("name 1 "+d [2])
print ("name 2 "+ d [3])
print (m.keys())
print (m.values())
Output:
name 1 malec
name 2 joy
{1: 'Jim', 2: 'malec', 3: 'joy', 4: 'mark'}
A dictionary employs keys instead of indexes to access values. Both square brackets [] and the get() function can be used with keys, if the dictionary does not have a key, KeyError is raised. In contrast, if the key cannot be retrieved, the get() method returns None.
Dictionaries are subject to change. Using the assignment operator, new objects can be created, or existing ones' values can be altered. If the key already exists, the existing value will be changed. If the key is missing, the dictionary is updated with a new (key: value) pair. As an example,
# manipulation and addition of Dict items
Using the pop() method, we can eliminate a specific item in a dictionary. After deleting items with any of the supplied keys, this function will return that item.
The popitem() method can be used to delete and return a key or value item pair from dictionaries.
Using the clear() method, all the items can be eliminated at once.
Deleting individual entries or the entire dictionary is likewise possible with the del keyword. Consider the following:
meters = {11: 5, 12: 8, 13: 7, 14: 17, 15: 75}
print(meters.pop(11))
Output:
{12: 8, 13: 7, 14: 17, 15: 75}
For the Boolean type, True and False are the default values. These figures are used to tell if the assertion stated is accurate. It's wrapped up in the bool class. True is any non-zero number or the character 'T', while false is any non-zero value or the character 'F'. Consider the following.
Keywords are not built-in names. They're regular variables as far as the Python language is concerned. If you assign to them, the built-in value will be overridden.
True and False, on the other hand, are not built-ins. Keywords are what they are. True and False, unlike many other Python keywords, are Python expressions. They can be used everywhere other expressions, such as 1 + 1, can be used because they're expressions.
It is possible to assign a Boolean value to variables, but not to True or False.
Because False/True is a Python keyword, you can't assign to it. True and False behave similarly to other numeric constants in this way. You can pass 1.5 to functions or assign it to variables, for example. It is, however, hard to put a value on 1.5. The Python expression 1.5 = 5 is incorrect. When processed, both 1.5 = 5 and False = 5 are invalid Python code and will result in a SyntaxError.
Python considers Booleans to be a numerical type. For all intents and purposes, that means they're numbers. To put it another way, Booleans can be used to perform mathematical operations and compared to numbers.
True and False can be thought of as Boolean operators that don't require any inputs. The result of one of these operators is always True, while the other is always False.
Sometimes it's helpful to think of Python's Boolean values as operators. This method, for example, can help you remember that they aren't variables. It is impossible to assign to True or False for the same reason you can't assign to +.
In Python, there are only two possible Boolean values. When there are no inputs to a Boolean operator, the result is always the same. As a result, the only two Boolean operators that do not take inputs are True and False.
Python Set refers to the data type's unordered collection. It's iterable, changeable (meaning you may change it after you've created it), and contains unique items. To construct the set, elements` sequence is given between curly brackets and separated by a comma, or the built-in method set() is used. It can have a variety of different values in it. Consider this scenario.
seta = set()
setb = {'Jane', 2, 3,'class'}
print (setb)
setb.add(10)
print (setb)
setb.remove(2)
print(setb)
Output:
{3, 'class', 'jane', 2}
{'class', 'Jane', 3, 2, 10}
{'class', 'jane', 3, 10}
Congratulations on completing this introduction to data type tutorial. In this tutorial, we covered the in-built data types provided by Python.
So far, all of the examples have just altered and presented constant data. In almost all projects, you'll want to build objects which vary in value as the program runs. In the next topic, we will look at sets in depth.
Hello! Welcome to the next lesson in this Python course. In the last session, we learned about python tracebacks and how to deal with them. A dictionary, like a list, is a collection of items, and we'll look at that in this tutorial as well.
This tutorial introduces you to the fundamentals of dictionaries in Python and teaches you how to work with dictionary data. After reading this article, you should be able to tell when and how to utilize a dictionary as a data type.
Data structures that use associative arrays, or dictionaries in Python, are known as dictionaries. Dictionaries store key-value pairs. Every pair of key-values has a corresponding value assigned to it.
With curly bracketed lists of value pairs, you can define a dictionary (). Each key and its corresponding value are separated by a colon (:):
The following is a definition of a dictionary that links a place's name to the MLB team that occupies that location:
The built-in dict() function can also be used to create a dictionary. Key-value pairs should be passed to dict() as an argument. In this case, a list of tuples works well:
The following is an alternate definition for MLB team:
Key values can be supplied as keyword arguments if they are simply strings. MLB team can also be defined in another way.
You can display the contents of a dictionary in the same way you do a list once it has been defined. When presented, the following is what each of the three definitions provided above looks like:
An alphabetical list of words and phrases is shown in the dictionary. When it comes to getting them back, however, none of it matters. There is no numerical index for dictionary elements:
Dictionary elements, of course, need to be accessible in some way. What if you can't find them using an index?
To get a value out of a dictionary, use the square bracketed key ([]):
Python throws an error if you try to use a key that doesn't exist in the dictionary:
It's as simple as setting a new key and value to the existing entries in a dictionary:
In order to make a change to an existing record, you can assign different value to the current key.
A record can be deleted by issuing the del command with the key you want to delete specified:
For some reason, the interpreter throws a Key Error whenever an undefined key or numeric index are used to retrieve a dictionary's keys.
A mistake has been made in both cases. However, [1] does not represent an index in the second instance.
To utilize an immutable object as a dictionary key, you'll discover later on in this lesson that it's possible. It follows that integers are perfectly acceptable:
The integers enclosed in square brackets [] appear to be indexes. It's only that they don't have anything to do with the dictionary's order. They're being treated as dictionary keys by Python. The same values can be obtained by defining the dictionary in the reverse order:
Despite the similarity in syntax, a dictionary cannot be treated as a list:
As a reminder, Python guarantees that the order of entries in a dictionary will be retained even if access to them is not required. Order matters when it comes to displaying items and iterating over the keys; this is how they'll appear when you see them. Items that are added to a dictionary are inserted in its final paragraph. Even after deletion, the remaining items retain their original order.
When all the other keys and values are known ahead of time, a dictionary can be defined as shown above by use of curly brackets and a value. It's a difficulty if you want to build a vocabulary on the fly.
Empty curly braces specify an empty dictionary, so that's where you want to start. Adding additional keys and values one at a time is possible.
It's the same as using any other dictionary once the dictionary has been constructed in this manner:
A secondary index or key is required to retrieve the values from the sublist or subdictionary:
Another advantage of dictionaries is that they don't require all of their entries to be of the same type. There are some strings, some integers, a list and a dictionary among the values in person.
The keys and values don't have to be the same.
Integers, floats, and Booleans make up three of the four keys. Although it isn't immediately clear how this could be of benefit, you never know.
Python dictionaries can be used in a variety of ways. As a part of the MLB_team, the baseball team's name can be found in a number of places. There is only one entity that can be used to identify an individual: the person.
There are few restrictions on the types of keys and values that can be stored in dictionaries, making them useful for a wide range of tasks. But there are a few exceptions to this rule. Continue reading for more information!
It is possible in Python to utilize almost any value as key in dictionary. You saw how to use integer, float, and Boolean values as keys like:
It's also possible to use pre-existing objects like types and functions in your code:
Dictionary keys, on the other hand, are subject to a few restrictions.
It is important to note that a single key can only be used in a dictionary once. It is not permitted to use two different keys. So, it doesn't make any sense to have more than one entry for the same key in the dictionary.'
You can't create a new key by introducing a new value to the current dictionary key; rather, you can simply replace the existing value.
Second-occurrence key names take precedence over first-occurrence ones in the dictionary-building process.
It's also important that a key in dictionary is of a type that cannot be changed. In the examples you've already seen, several of the types that are immutable, such as integers, floating points, strings, and Bools, have been used as dictionary keys.
Tuples, by virtue of their immutability, can also be used as dictionary keys:
When an immutable type is needed, a tuple is preferable to an array. One of them is this.)
Lists and dictionaries can't be used as a dictionary key because of the mutability of both:
For a dictionary key to work, an object does not necessarily need to be immutable. It must be possible to send an item via a hash function, which means it must be hashable. For database lookup and comparison, data of any size can be hashed using a hash function to produce a fixed-size result known as a hash (or simply hash).
When an object is hashable, the built-in hash() method delivers its hash value; otherwise, it raises an exception.
As you've learned so far, immutable types and containers (lists/dictionaries) that can be hashed are all built-in. For the time being, you can consider the terms "hashable" and "immutable" to be nearly interchangeable.
You'll see changeable objects that are also hashable in upcoming lectures.
Dictionary values, on the other hand, are unrestricted. In fact, there is nothing at all. For example, lists and dictionaries can be mutated and user-defined objects can be created in Python.
In a dictionary, there is no limit to the number of times a single value can appear.
A large number of the built-in and available operators and functions for working with texts, lists, or tuples will be known to you at this point. As well as other dictionaries, several of these are useful.
Using the in and not in operators, for example, you can determine whether or not an operand is a dictionary key.
A key that is not in the dictionary can be avoided by using the in operator and short circuit evaluation:
Dictionary key-value pairs are counted using the len() method.
Similarly, to strings and lists, dictionaries include built-in methods that can be used. Although lists and dictionaries share names in some circumstances, it is not always the case. Since various kinds might have methods with the same names, this is totally appropriate when discussing object-oriented programming.)
There are a few approaches that can be used for dictionaries:
Clears elements in the dictionary.
The function d.clear() removes all key-value pairs from the dictionary d:
Whether or not a key exists in the dictionary is checked, and the value associated with it is returned.
This method can be used to retrieve the value of any key without having to verify that the key exists.
If a value matching the supplied key (<key>) is discovered in dictionary d, Get (<key>) returns it. If it is unable to locate the appropriate key, this procedure returns 0.
We're going to use -1 instead of None in case <key> could not be located and the <default> argument had been provided.
The key-values` list in a dictionary is returned by this command.
items(‘value’) will return a tuple`s list containing the values in d. Key value tuples consist of two items: the key and the value.
This function will return a list of the dictionary's keys.
A list of all d keys can be found using d.keys()
Values of dictionary are returned in response to this method.
The list of all values in d is returned by d.values()
If d contains any duplicate values, all of those values will be returned:
A "view object," which is a collection of objects, keys, and values, is returned by these functions. The keys and values of a dictionary can be seen through a similar window in a dictionary view object, the keys and values of the dictionary are returned as an array by these methods.
A key is removed from the dictionary and its value is returned if it exists.
pop(key) will remove key and return its related key when <key> is in d:
In a dictionary, this function removes one key-value pair.
d.popitem() will remove and return any last key pair added to d.
Merges the dictionary and iterable key-value pairs.
A dictionary can be updated with update(<obj>), which merges all of the items from obj>. For each key in obj>:
If the value pairs from obj do not already exist in d, they are added to d.
Changes to the value of the key in d are made by use of values from <obj>.
The following is an example of how two dictionaries can be combined:
Therefore, its value is set to 200 because b is contained in d1, which is derived from d2's entry for that key. D1 does not include the key d, hence the key-value pair is taken from d2.
Key-value pairs can also be utilized to define a dictionary using the dict() function. As an example, a list of tuples, such as obj:
It is also possible to specify the values to merge in the form of a list of keywords:
Throughout this course, you learned how to read and manipulate the data in a Python dictionary.
Lists and dictionaries are two of Python's most commonly used data structures. It is clear from the comparison that they have many commonalities yet are different in how their elements can be found. Index numbers are used to locate items in lists, and keys are used to locate items in dictionaries.
Therefore, lists and dictionaries are appropriate for different circumstances. You should now be able to tell whether one or the other is the best option in a given case.
Python sets are the next topic you'll study. Unlike lists and dictionaries, the set is not a simple collection of elements.
