How to use python on windows

January 13, 2022

Tutorial: Installing Python on Windows

Python is a popular open-source, high-level programming language. It’s intuitive, and it offers many helpful tools and libraries — Python is a powerful data science asset to have in your toolkit. To start working with Python, we first need to download it and install it on our operating system (in this case, Windows).

There are two main ways of installing Python on Windows: installation from the official Python website or from Anaconda, a convenient distribution of Python and R programming languages. Choose the first option if you are a programmer using Python for various purposes: creating websites, network programming, developing software applications. If instead, your work is focused on data science and machine learning, then Anaconda is the best choice for you. Essentially, Anaconda is a powerful data science platform that provides more than 1500 built-in Python and R data science packages — and also the most popular Python IDEs. With Anaconda, you can choose to use the graphical user interface (GUI) instead of the command line. Also, it is adapted for processing large amounts of data, easily working with different environments and applications, and managing the package versions.

Check if Python is already installed

Before starting the installation process, we want to check if Python is already installed on your computer (e.g., by a previous user), and if so, which version of Python. To do so, open the command line application Command Prompt (in Windows search, type cmd and press Enter) or Windows PowerShell (right-click on the Start button and select Windows PowerShell) and type there python -V. If you found that Python is already installed on your computer and want to check the path of the installation, run where.exe python in the command line application.

Install Python on Windows from the official Python website

If you see that Python isn’t installed, you can use the official Python website to install it.

Step 1. Open the Python Releases for Windows page, select Python version, and download Python executable installer

Here you can choose whether to download Python 2 or Python 3 (or both). Later, we will discuss in more detail the technical steps of downloading and installing both Python 2 and Python 3, but first, let’s determine which of them (or both) you really need.

Python 3 is a more recent version of Python released in 2008 and designed to fix the issues in Python 2. In comparison to Python 2, Python 3 has a simpler and more intuitive syntax, it offers a wide range of useful libraries (especially for data science), and a large community of Python developers maintain it. In contrast, Python 2 is no longer supported. Hence, downloading the latest Python 3 release is generally the best choice if you aren’t certain which version to use. You will most likely need only Python 3 if you’re going to work with new projects.

However, in some cases, you may also need Python 2. For example, if some of your company’s projects are written in Python 2, which is incompatible with Python 3, you might have to run older scripts. Also, sometimes, you may want to use a Python package that hasn’t been updated in Python 3. In such situations, You’ll need Python 2.

If you select the latest Python 2 release to download, choose Windows x86-64 MSI installer, which will identify your Windows version (32-bit or 64-bit) automatically:

To download the latest Python 3 release, you have to manually choose the installer that suits your Windows version:

Step 2. Run the installer

Let’s follow this process step-by-step separately for Python 2 and Python 3. Remember that, depending on your needs, you can install either one of them or both of them. It will cause no issues, and you will always be able to choose which Python version to work in.

Python 2.

Run the downloaded executable file for Python 2 that you will find in your Downloads folder. Select at each step the following options:

After that, just confirm everything at each pop-up window to complete the installation.

Now you have the latest Python 2 release successfully installed.

Python 3.

Download installer for Python 3, and find it in your Downloads folder. On the first pop-up window, select both checkboxes at the bottom to enable adding Python to your path in Windows automatically. Then select Install Now:

The installation process can take a few minutes. Then, in the next window, select Disable path length limit to avoid potential issues with long path names in the future:

The latest Python 3 release has been installed on your computer.

Step 3. Verify if Python was successfully installed on Windows

If you installed only one version of Python, open the command line and run python -V. If you installed both Python 2 and Python 3, you have to make a small adjustment that we will discuss in the following (optional) step.

Step 4 (only if you installed both Python 2 and Python 3). Reassign system variables

This step is necessary for being able to easily access both Python versions from the command line.

If you now run python in the command line, you will see only the version of Python 2 (in our case, Python 2.7.18). It happened because, even though you enabled the system path for both Python versions, the installers were saved as the variable sets of different levels of the path: system level (Python 2) and user level (Python 3). In such cases, priority is given to the system path, hence to Python 2. You can verify it by exploring the environment variables of Windows: in Windows search, type advanced system settings, select View advanced system settings, open the Advanced tab, click the Environment Variables button. In the pop-up window, you will see that Python 3 is related to the user variables, while Python 2 is related to the system variables:

To fix this issue, you can assign different access to Python 3: python3 instead of just python:

1. Open the File Explorer app in Windows search, and find the folder where you installed Python 3. By default, the path should be the following: C:UsersusernameAppDataLocalProgramsPythonPython310
2. Make a copy of the python.exe file, and rename this copy as python3.exe:

1. Re-open the command line.
2. Now, you can return to Step 3 and verify the Python version for both Python 2 and Python 3:

Install Python on Windows from Anaconda Navigator

Instead of the full installer from the official Python website, you can use open-source Anaconda Navigator, a popular Python and R distribution for data science and machine learning tasks.

Step 1. Open the official Anaconda website, and select Individual Edition in the menu of Products

Step 2. Download the installer

The system will automatically suggest the most suitable package for your operating system (Windows):

Step 3. Run the installer

Find the downloaded installer for Anaconda in your Downloads folder, and run it:

During the installation process leave all the options as default on all the screens. In one of the windows, though, you can decide to change the installation location, but it is generally best to leave it as it is:

The installation process can take a few minutes.

Now Anaconda has been successfully installed on your computer.

How to run your first Python code on Windows

Now that you have installed Python, whether from the official Python website or using Anaconda Navigator, you’re ready to run your first Python code.

If you installed Python from the official Python website

Type idle in Windows search, and select the necessary version of IDLE (in the case you installed different Python versions, there will be corresponding versions of IDLE):

Now you can start coding, even in parallel in different Python versions:

If you installed Python from Anaconda Individual Edition

1. Type anaconda in Windows search, and open Anaconda Navigator:

1. Choose from many applications the most suitable one for your purposes. For example, you can opt for Jupyter Notebook, a popular data science application for creating and sharing documents combining code, charts, and storytelling:

1. Navigate to the folder where you are going to save your code, and create a new Python notebook:

1. Start coding:

How to update Python to the latest version on Windows

If you installed Python from the official Python website

Just as you did when initially installing Python, open the Python Releases for Windows page, select the latest Python release, download and run the suitable installer.

If the latest release is just a new Python patch of the same major version as your current version (e.g., 3.9.8 and 3.9.9), you will see the following option in the pop-up window:

In this case, the latest Python version will be installed on your computer, and the previous version will be removed. You need to restart your machine afterward.

If the latest release is a new major version of Python with respect to your current version (e.g., 3.9 and 3.10), you will see the same option as on the initial installation:

In this case, the latest Python release will be installed on your computer but also the previous version will remain. If necessary, you can uninstall it manually using the Control Panel.

If you installed Python from Anaconda Individual Edition

Type anaconda in Windows search, and open Anaconda Prompt. To update the Python version for the base (root) environment to the latest Python version available for the current Anaconda release, run conda update python.

(Side note: You may need first to update Anaconda itself to the latest version, by running conda update conda.)

In the snapshot below, you can see that after updating the Python version on Anaconda to the latest version, nothing actually changed: the version remained 3.9.7, instead of being updated to the latest (currently) Python version 3.10.1:

This happened because Python 3.9.7 is the latest possible Python version available for the current Anaconda release.

You can wait for the next Anaconda release, or consider creating a new virtual environment on Anaconda:

conda create -n python10 python=3.10

Above, you created a virtual Anaconda environment called python10 (feel free to give it any other name), with the official latest version Python 3.10.

Now, to be able to work in this environment, you have to activate it, running conda activate python10:

Notice how the name of the active environment changed from base to python10. Also, notice that if you check the Python version, you will see that it has been updated to Python 3.10.0.

Unfortunately, it isn’t possible to specify the exact patch of the latest version when creating a new virtual environment (meaning that you can only write python=3.10 and not python=3.10.1).

You can continue coding in Python 3.10.0 in the created virtual environment from the command line. Alternatively, since Anaconda is, first of all, a convenient GUI Interface, you can go again to Anaconda Navigator, select the new environment, install any applications you need (if they are available for that environment), and start working there.

You can also easily create a new virtual environment with a necessary Python version directly from Anaconda Navigator:

1. Open the Environments tab of Anaconda Navigator.
2. Press the Create button at the bottom of the screen.
3. Give a name to the new environment, and select the version of Python.

A new environment called python10_new has been created:

1. Go to the Home tab, where the new environment will be already selected automatically.
2. Install any available applications you need and start coding.

Conclusion

In this tutorial, you have learned how to correctly download and install Python both from the official website and Anaconda, update it to the latest version if necessary, and run Python scripts on Windows. Now you have all the necessary tools and settings to start working in Python.

python-on-windows

A step-by-step guide on installing Python and using the Command Prompt for Windows

• Version: 1.1.0
• Date: 2017-01-03
• Author: Alberto Pettarin (contact)
• License: Creative Commons Attribution 4.0 International (CC BY 4.0)

Overview

Do you want to run a Python program under Windows,
but you have no experience using the Command Prompt?

This guide is for you!

I will walk you through the installation of Python
and I will explain the basics of the Command Prompt.

After reading this page (and practicing a bit),
you should be able to run a Python program
confidently and safely.

What Is Python?

Python is a
high-level, general-purpose programming language
which allows people to easily create and share programs
for a variety of applications.

The Python project is a free (libre)/open source software (FLOSS) initiative,
managed by the Python Software Foundation.
You can download, install, and use Python for free
on several platforms,
including Linux, Mac OS X, and Windows computers.

Python enables the development of FLOSS programs,
which are created for free
by millions of volunteers around the globe
and shared in source code form.
This means that the end user
who receives or downloads a Python program
can actually check that the program does what
is supposed to do, and nothing more
(unlike closed-source programs,
which send personal information to third parties,
show you advertisements, or
damage your computer).

More details on Python can be found on the
official Python page
and on its
Wikipedia page.

In practice, to use a Python program you need two pieces of software:

• the Python interpreter, which is the «master» program
  that reads the source code of a Python program,
  and «execute» it; and
• the source code of the Python program,
  usually consisting of one or more files with .py extension,
  which performs the specific task you are interested in.

This guide explains how to install the former,
and it shows how to run the latter
in the Command Prompt of Windows,
with a complete, real-life example.

Installing Python On Windows

The preliminary step consists in installing
the Python interpreter (i.e., the «master program»)
on your computer.

Installing Python is a one-time operation.
If you already installed Python in the past
(for example, to run a different program),
you do not need to install it again,
and you can skip to the next section.

Step 0: Should I Get Python 2 Or Python 3?

At the time of writing (2017-01-01),
there are two main versions of Python:
Python 2 (2.7.13) and Python 3 (3.6.0).

Discussing the technical differences between these two versions
is beyond the scope of this guide.
It suffices to say that
some Python programs work with both versions of Python,
while other Python programs work only
with Python 2 but not with Python 3,
or vice versa.

You should get the version of Python that the program
you are interested in recommends.
If the latter does not specify a version,
get the latest Python 3 version available.
If you later discover that your Python program
does not work with the Python version you installed,
do not worry: just uninstall it, and install the other one!

In the rest of the guide we assume you need Python 3.

Step 1: Download The Installer

First, open your Web browser and
go to https://python.org/:

Click on the Download > Latest Python 3.6.0 link.

You will get a page listing all the new features of Python 3.6.0:

Scroll down until you see the list of available downloads:

If you have a recent Windows computer,
very likely it is a 64-bit machine,
so you should download the file labeled Windows x86-64 executable installer,
and save it on your Download folder or on your Desktop:

Downloading the file will take from few seconds to a few minutes,
depending on the bandwidth of your Internet connection.

(If you have an older PC that you know is a 32-bit computer,
download the Windows x86 executable installer instead.
You can tell whether your PC is a 32-bit or a 64-bit machine
by reading the System Information in the Windows Control Panel.)

Step 2: Install Python

Double-click on the file you just downloaded
to start the installation wizard:

By default, the Add Python 3.6 to PATH option is disabled,
but you should select it,
as it makes running Python programs much much easier.

Most users should click the Install Now button,
which installs Python with the default settings.
(If you want to personalize your installation
or you are told to enable some advanced features,
click on the Customize installation option instead.)

The installer might ask you for administrative privileges
or for confirmations like the following:

You can safely answer Yes.

A progress bar will appear:

until the installation completes with the following message:

Starting with Python 3.6.0,
it is recommended to click on
the Disable path length limit option,
before closing the installer.
If you do so, you will get a final confirmation dialog:

You can terminate the installation by clicking the Close button.

Congratulations, you have your first Python installation under your belt!

Using The Command Prompt

Most Python programs are command line interface (CLI) utilities,
which means that they are not operated
via a graphical user interface (GUI),
also known as «the program window».
Instead, they must be executed
in the Command Prompt of Windows,
also known as «shell» or «terminal».

Running a CLI program means
typing a command string on the Command Prompt of Windows,
following a certain syntax
which depends on what the program is supposed to do.
You can think of this act as reciting the «right spell»
to get your job done.

Opening A Command Prompt

To open the Command Prompt,
locate the Command Prompt icon in your Start menu
(or use the search bar):

Click on the icon. A black window appears:

The first two lines printed in the window
show the version of the Command Prompt.
The last line, which reads C:UsersIEUser> in the screenshot above,
is the prompt, where you can actually type commands.

The prompt line always starts
with the location of the working directory,
that is, the folder where the command prompt is currently acting upon
(C:UsersIEUser in the screenshot above),
and ends with the > character.

The prompt normally opens in the home directory of the current user:
in fact, we are in C:UsersIEUser,
because the user is called IEUser.
If your Windows username is Olga,
it is likely you will see
C:UsersOlga instead.

(Different versions of Windows might have different paths for home directories.)

In the documentation of Python programs you might find a $ character
before examples of commands, as follows:

$ python my_awesome_program.py

because on Linux and Mac OS X machines
the terminal prompt is usually a $ character.

You should not type the $ character,
it is just a placeholder for your actual prompt.
For any practical purpose,
you can mentally replace the $ with your actual prompt,
like C:UsersIEUser> in the example above,
as if the documentation was as follows:

C:UsersIEUser> python my_awesome_program.py

(You will actually type only python my_awesome_program.py and
hit the Enter/Return key.)

The Three Safety Rules

By issuing commands on the Command Prompt,
you can accidentally delete your own files or damage Windows,
so you must be careful.

Do not be afraid or discouraged:
you do not stop using knives just because
you can cut your fingers with them!

By following Three Safety Rules,
you can operate the prompt safely:

1. Never issue a command without understanding what it does,
   and only run programs obtained from developers that you trust.
2. If anything happens in the prompt that you do not understand,
   you can simply click on the «X» on the right top corner
   to close the Command Prompt window
   (and hopefully nothing bad will happen to your files).
3. Always copy your Python program in a separate
   folder, and always make copies of your input files in it,
   so that you can just throw away the Python program folder
   if something goes wrong, and start over.

Changing The Working Directory (cd)

As said above, the command prompt normally opens
in the home directory of your user:

If you want to change the current working directory,
you can use the cd command.
For example, to move to the C: directory
(the root directory of your C: drive),
you type cd C:
and press the Enter/Return key:

Notice that the prompt changed to C:>.

Listing The Contents Of The Working Directory (dir)

If you want a list of the files or subdirectories
contained in the current working directory,
issue the dir command, without arguments:

The prompt shows a list of directories and files
that are contained in the C: drive:
in the above screenshot they are
BGinfo, PerfLogs, …, Windows.

At this point, if you want to enter the Users directory,
you can simply type cd Users, and so on.

If you want to go up one level, type cd ..
(two full stop character).
For example, if you are in C:Users and give a cd ..,
you will end up in C:.

If you want to clear the prompt window, use the cls command.

Checking That Python Is Installed Correctly

If you selected the Add Python to PATH option,
you can run the Python interpreter (and any Python program)
from any current working directory.

To check this, give the python --version command:

The Python version will be printed
(e.g., Python 3.6.0)
and you will get back to the Windows prompt.
You just ran Python in non-interactive mode,
meaning that you provided a precise command
(«Python, print the version number you are»),
the Python interpreter performed what you asked for,
and then it returned control to the Command Prompt of Windows.

The non-interactive mode is how most Python programs work.

If you forget to add the --version parameter
after the python command,
you will enter the interactive Python shell instead:

Notice how the prompt changed to >>>.

To exit the Python shell, and return to the Command Prompt,
just type quit() and hit the Enter/Return key:

Discussing the interactive shell is beyond the scope of this guide,
since most programs you are interested in are non-interactive.

Running A Python Program

Excellent, now you have all the tools required
to run a Python program on the command line.

As an illustration,
I will use my simple Python script
export-kobo,
which reads annotations and highlights
from the database file of a Kobo eReader device (KoboReader.sqlite),
and prints them on the prompt or exports them to an output file.

Step 1: Download The Source Code

First, download the source code of the Python program you want to run.

This usually implies downloading either a single Python source code file
(with extension .py), or a ZIP file containing several Python source code files
and other resource files that you need to uncompress somewhere on your disk.

The exact details depend on your Python program,
hence be sure to carefully read its install documentation.
You can download the prescribed files with your browser,
and then copy/uncompress them using the Windows graphical file manager.

In our example, we download the raw file
export-kobo.py
from the GitHub repository.

Remember Safety Rule 3
(«copy your Python files into a separate folder»)?

We put the downloaded export-kobo.py file
in a new folder C:export-kobo:

Note that we also copied
the KoboReader.sqlite file
(the input of our Python program)
from our Kobo eReader
to the same folder.

Step 2: Open A Command Prompt And cd There

Then, open a Command Prompt as explained above,
and change the current working directory to the folder
where you put your Python program source files.

In our example, cd C:export-kobo:

A simpler alternative to using the cd command
takes advantages of the Windows file explorer.
Just navigate the file explorer to the folder
where your Python code is:

and select the
File > Open command prompt > Open command prompt
menu:

you will get a new Command Prompt window,
already located at the correct directory:

Step 3: Run The Python Program

At this point, we are ready to run our program.

Type python export-kobo.py KoboReader.sqlite --list and hit Enter/Return:

The Python interpreter will load our export-kobo.py program,
and run it with arguments KoboReader.sqlite and --list.

Clearly, the semantics of the arguments vary from program to program,
depending on what each program is supposed to do.

In our case, export-kobo.py will read the file
whose name is passed as the first parameter (KoboReader.sqlite)
and it will list (--list option) the titles of all the eBooks
with annotations or highlights in the database.

If we specify different command arguments, for example
python export-kobo.py KoboReader.sqlite --csv --output exported.csv,
we will get a different behavior:

In particular, this second command exported all the information
contained in the KoboReader.sqlite file into
the newly created file named exported.csv in CSV format:

You must check the documentation of your Python program
to know the semantics of its arguments.

Usually, if you run a Python program without arguments
you will get a synopsis of the accepted arguments:

If a -h or --help argument is given,
then a more verbose help message will be printed:

Congratulations, now you should be able
to download and run a Python program on your own!

Acknowledgments

• Louise Schofield nee Stokes for suggesting using the file explorer menu
  to open the command prompt at a given directory