Run Python on Your Computer

The Core lessons run Python in the browser. Local Python is optional at this stage, but it becomes useful when you want to keep scripts as ordinary files or work without this page open.

Check for Python 3

A terminal is a text window for running commands. On macOS, open Terminal from Spotlight. On Windows, open PowerShell from the Start menu. On Linux, open the terminal application supplied with your desktop.

On macOS or Linux, try:

python3 --version

In Windows PowerShell, try:

python --version

If Windows does not recognize python, also try py --version. A result beginning with Python 3 shows that the command found Python 3. The final version number may differ. If neither command works, follow the installation instructions for your operating system at python.org.

After installation, close and reopen the terminal before checking again. This gives the terminal a chance to see the new command.

Save a Python File

Before saving the file, ask the terminal which folder it has opened. On macOS or Linux, run pwd. In PowerShell, run Get-Location. The command displays a folder path. Save a plain-text file named temperature_report.py in that folder, and put this source code inside it:

The .py ending identifies the file as Python source. A word processor is not suitable because it may store formatting data alongside the text. Use a code editor or another editor that saves plain text.

Run the Saved File

Because the file is in the folder displayed by the terminal, we can run it without changing folders. On macOS or Linux, use:

python3 temperature_report.py

In Windows PowerShell, use:

python temperature_report.py

If py --version was the command that worked earlier, use py temperature_report.py instead.

The report should match the browser result:

total: 82
count: 4
mean: 20.5

If Python says that it cannot open the file, check the folder and filename. On macOS or Linux, pwd shows the current folder and ls lists its contents. In PowerShell, Get-Location shows the current folder and Get-ChildItem lists its contents. The list should contain temperature_report.py.

The Python command and the source filename have different roles:

• python3, python, or py starts Python;
• temperature_report.py names the source file Python should run.

Keep the Browser Path Available

Local setup differs across computers, operating systems, school machines, and managed work devices. It should not block the Python curriculum. If local setup becomes distracting, return to the browser runner and continue the Core path. You can revisit this page when a later file-based or numerical project makes a local environment useful.