How do I know if an app is running in Python?

In this tutorial, you will use Python 3 to create the simplest Python "Hello World" application in Visual Studio Code. By using the Python extension, you make VS Code into a great lightweight Python IDE (which you may find a productive alternative to PyCharm).

This tutorial introduces you to VS Code as a Python environment - primarily how to edit, run, and debug code through the following tasks:

• Write, run, and debug a Python "Hello World" Application
• Learn how to install packages by creating Python virtual environments
• Write a simple Python script to plot figures within VS Code

This tutorial is not intended to teach you Python itself. Once you are familiar with the basics of VS Code, you can then follow any of the programming tutorials on python.org within the context of VS Code for an introduction to the language.

If you have any problems, you can search for answers or ask a question on the Python extension Discussions Q&A.

Prerequisites

To successfully complete this tutorial, you need to first setup your Python development environment. Specifically, this tutorial requires:

• Python 3
• VS Code application
• VS Code Python extension

Install Visual Studio Code and the Python Extension

1. If you have not already done so, install VS Code.

2. Next, install the Python extension for VS Code from the Visual Studio Marketplace. For additional details on installing extensions, see Extension Marketplace. The Python extension is named Python and it's published by Microsoft.

   

Install a Python interpreter

Along with the Python extension, you need to install a Python interpreter. Which interpreter you use is dependent on your specific needs, but some guidance is provided below.

Windows

Install Python from python.org. You can typically use the Download Python button that appears first on the page to download the latest version.

Note: If you don't have admin access, an additional option for installing Python on Windows is to use the Microsoft Store. The Microsoft Store provides installs of supported Python versions.

For additional information about using Python on Windows, see Using Python on Windows at Python.org

macOS

The system install of Python on macOS is not supported. Instead, a package management system like Homebrew is recommended. To install Python using Homebrew on macOS use brew install python3 at the Terminal prompt.

Note On macOS, make sure the location of your VS Code installation is included in your PATH environment variable. See for more information.

Linux

The built-in Python 3 installation on Linux works well, but to install other Python packages you must install pip with .

Other options

• Data Science: If your primary purpose for using Python is Data Science, then you might consider a download from Anaconda. Anaconda provides not just a Python interpreter, but many useful libraries and tools for data science.

• Windows Subsystem for Linux: If you are working on Windows and want a Linux environment for working with Python, the Windows Subsystem for Linux (WSL) is an option for you. If you choose this option, you'll also want to install the WSL extension. For more information about using WSL with VS Code, see VS Code Remote Development or try the Working in WSL tutorial, which will walk you through setting up WSL, installing Python, and creating a Hello World application running in WSL.

Verify the Python installation

To verify that you've installed Python successfully on your machine, run one of the following commands (depending on your operating system):

• Linux/macOS: open a Terminal Window and type the following command:

  python3 --version
  

• Windows: open a command prompt and run the following command:

  py -3 --version
  

If the installation was successful, the output window should show the version of Python that you installed.

Note You can use the py -0 command in the VS Code integrated terminal to view the versions of python installed on your machine. The default interpreter is identified by an asterisk (*).

Start VS Code in a workspace folder

By starting VS Code in a folder, that folder becomes your "workspace". VS Code stores settings that are specific to that workspace in

py -3 --version

Using a command prompt or terminal, create an empty folder called "hello", navigate into it, and open VS Code (

py -3 --version

py -3 --version

mkdir hello
cd hello
code .

Note: If you're using an Anaconda distribution, be sure to use an Anaconda command prompt.

Alternately, you can run VS Code through the operating system UI, then use File > Open Folder to open the project folder.

Select a Python interpreter

Python is an interpreted language. Thus, in order to run Python code and get Python IntelliSense, you must tell VS Code which interpreter to use.

From within VS Code, select a Python 3 interpreter by opening the Command Palette (⇧⌘P (Windows, Linux Ctrl+Shift+P)), start typing the Python: Select Interpreter command to search, then select the command. You can also use the Select Python Environment option on the Status Bar if available (it may already show a selected interpreter, too):

The command presents a list of available interpreters that VS Code can find automatically, including virtual environments. If you don't see the desired interpreter, see Configuring Python environments.

Note: When using an Anaconda distribution, the correct interpreter should have the suffix

py -3 --version

3, for example

py -3 --version

4.

Selecting an interpreter sets which interpreter will be used by the Python extension for that workspace.

Note: If you select an interpreter without a workspace folder open, VS Code sets

py -3 --version

5 in User scope instead, which sets the default interpreter for VS Code in general. The user setting makes sure you always have a default interpreter for Python projects. The workspace settings lets you override the user setting.

Create a Python Hello World source code file

From the File Explorer toolbar, select the New File button on the

py -3 --version

Name the file

py -3 --version

By using the

py -3 --version

Note: The File Explorer toolbar also allows you to create folders within your workspace to better organize your code. You can use the New folder button to quickly create a folder.

Now that you have a code file in your Workspace, enter the following source code in

py -3 --version

msg = "Hello World"
print(msg)

When you start typing

mkdir hello
cd hello
code .

IntelliSense and auto-completions work for standard Python modules as well as other packages you've installed into the environment of the selected Python interpreter. It also provides completions for methods available on object types. For example, because the

mkdir hello
cd hello
code .

mkdir hello
cd hello
code .

Feel free to experiment with IntelliSense some more, but then revert your changes so you have only the

mkdir hello
cd hello
code .

mkdir hello
cd hello
code .

For full details on editing, formatting, and refactoring, see Editing code. The Python extension also has full support for Linting.

Run Hello World

It's simple to run

py -3 --version

The button opens a terminal panel in which your Python interpreter is automatically activated, then runs

mkdir hello
cd hello
code .

mkdir hello
cd hello
code .

There are three other ways you can run Python code within VS Code:

• Right-click anywhere in the editor window and select Run Python File in Terminal (which saves the file automatically):

  

• Select one or more lines, then press Shift+Enter or right-click and select Run Selection/Line in Python Terminal. This command is convenient for testing just a part of a file.

• From the Command Palette (⇧⌘P (Windows, Linux Ctrl+Shift+P)), select the Python: Start REPL command to open a REPL terminal for the currently selected Python interpreter. In the REPL, you can then enter and run lines of code one at a time.

Configure and run the debugger

Let's now try debugging our simple Hello World program.

First, set a breakpoint on line 2 of

py -3 --version

mkdir hello
cd hello
code .

Next, to initialize the debugger, press F5. Since this is your first time debugging this file, a configuration menu will open from the Command Palette allowing you to select the type of debug configuration you would like for the opened file.

Note: VS Code uses JSON files for all of its various configurations;

msg = "Hello World"
print(msg)

These different configurations are fully explained in Debugging configurations; for now, just select Python File, which is the configuration that runs the current file shown in the editor using the currently selected Python interpreter.

You can also start the debugger by clicking on the down-arrow next to the run button on the editor, and selecting Debug Python File in Terminal.

The debugger will stop at the first line of the file breakpoint. The current line is indicated with a yellow arrow in the left margin. If you examine the Local variables window at this point, you will see now defined

mkdir hello
cd hello
code .

A debug toolbar appears along the top with the following commands from left to right: continue (F5), step over (F10), step into (F11), step out (⇧F11 (Windows, Linux Shift+F11)), restart (⇧⌘F5 (Windows, Linux Ctrl+Shift+F5)), and stop (⇧F5 (Windows, Linux Shift+F5)).

The Status Bar also changes color (orange in many themes) to indicate that you're in debug mode. The Python Debug Console also appears automatically in the lower right panel to show the commands being run, along with the program output.

To continue running the program, select the continue command on the debug toolbar (F5). The debugger runs the program to the end.

Tip Debugging information can also be seen by hovering over code, such as variables. In the case of

mkdir hello
cd hello
code .

1, hovering over the variable will display the string

msg = "Hello World"
print(msg)

3 in a box above the variable.

You can also work with variables in the Debug Console (If you don't see it, select Debug Console in the lower right area of VS Code, or select it from the ... menu.) Then try entering the following lines, one by one, at the > prompt at the bottom of the console:

msg
msg.capitalize()
msg.split()

Select the blue Continue button on the toolbar again (or press F5) to run the program to completion. "Hello World" appears in the Python Debug Console if you switch back to it, and VS Code exits debugging mode once the program is complete.

If you restart the debugger, the debugger again stops on the first breakpoint.

To stop running a program before it's complete, use the red square stop button on the debug toolbar (⇧F5 (Windows, Linux Shift+F5)), or use the Run > Stop debugging menu command.

For full details, see Debugging configurations, which includes notes on how to use a specific Python interpreter for debugging.

Tip: Use Logpoints instead of print statements: Developers often litter source code with

mkdir hello
cd hello
code .

0 statements to quickly inspect variables without necessarily stepping through each line of code in a debugger. In VS Code, you can instead use Logpoints. A Logpoint is like a breakpoint except that it logs a message to the console and doesn't stop the program. For more information, see in the main VS Code debugging article.

Install and use packages

Let's now run an example that's a little more interesting. In Python, packages are how you obtain any number of useful code libraries, typically from PyPI. For this example, you use the

msg = "Hello World"
print(msg)

msg = "Hello World"
print(msg)

msg = "Hello World"
print(msg)

Return to the Explorer view (the top-most icon on the left side, which shows files), create a new file called

msg = "Hello World"
print(msg)

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 20, 100)  # Create a list of evenly-spaced numbers over the range
plt.plot(x, np.sin(x))       # Plot the sine of each x point
plt.show()                   # Display the plot

Tip: If you enter the above code by hand, you may find that auto-completions change the names after the

msg = "Hello World"
print(msg)

9 keywords when you press Enter at the end of a line. To avoid this, type a space, then Enter.

Next, try running the file in the debugger using the "Python: Current file" configuration as described in the last section.

Unless you're using an Anaconda distribution or have previously installed the

msg = "Hello World"
print(msg)

To install the

msg = "Hello World"
print(msg)

msg = "Hello World"
print(msg)

A best practice among Python developers is to avoid installing packages into a global interpreter environment. You instead use a project-specific

msg
msg.capitalize()
msg.split()

Note: For additional information about virtual environments, see . v

1. Create a virtual environment using the Create Environment command

   From within VS Code, you can create non-global environments, using Venv or Anaconda, by opening the Command Palette (⇧⌘P (Windows, Linux Ctrl+Shift+P)), start typing the Python: Create Environment command to search, and then select the command. You can also trigger the Python: Create Environment command through the Getting Started with Python page.

   The command presents a list of environment types, Venv or Conda. For this example, select Venv.

   

   The command then presents a list of interpreters that can be used for your project.

   

   After selecting the desired interpreter, a notification will show the progress of the environment creation and the environment folder will appear in your workspace.

   

   The command will also install necessary packages outlined in a requirements/dependencies file, such as

   msg
   msg.capitalize()
   msg.split()
   

   4,

   msg
   msg.capitalize()
   msg.split()
   

   5, or

   msg
   msg.capitalize()
   msg.split()
   

   6, located in the project folder.

   Note: If you want to create an environment manually, or run into error in the environment creation process, visit the page.

2. Ensure your new environment is selected by using the Python: Select Interpreter command from the Command Palette.

   

3. Install the packages

   # Don't use with Anaconda distributions because they include matplotlib already.
   
   # macOS
   python3 -m pip install matplotlib
   
   # Windows (may require elevation)
   python -m pip install matplotlib
   
   # Linux (Debian)
   apt-get install python3-tk
   python3 -m pip install matplotlib
   

4. Rerun the program now (with or without the debugger) and after a few moments a plot window appears with the output:

   

5. Once you are finished, type

   msg
   msg.capitalize()
   msg.split()
   

   7 in the terminal window to deactivate the virtual environment.

For additional examples of creating and activating a virtual environment and installing packages, see the Django tutorial and the Flask tutorial.

Next steps

You can configure VS Code to use any Python environment you have installed, including virtual and conda environments. You can also use a separate environment for debugging. For full details, see Environments.

To learn more about the Python language, follow any of the programming tutorials listed on python.org within the context of VS Code.

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