In the last post, we ran some very basic python code directly in a python interactive session. But what would a more realistic example of python code look like? To make our lives easier, the most basic thing we need is a text editor (not a word processor). This will allow us to write and save python code as a file with a .py file extension (e.g. example_script.py).
We could just use Notepad on Windows, TextEdit on Mac or the built in editor on Linux. But there are fancier text editors out there that use syntax highlighting and formatting to make it easier to read our code. Choose whatever text editor you want.
Two free, cross-platform options are VS Code and Atom. VS Code was created by Microsoft. Atom was created by Github, which is now owned by Microsoft. To be extra confusing and hip, I currently use VS Codium.
If you don't care (you shouldn't), download and install VS Code. Then install the Python Extension for VS Code, to get syntax highlighting and other useful tools.
.py fileOnce you have a text editor installed, open it and create a new file. Save it with the .py file extension. When choosing a filename, I recommend keeping it short, and all lowercase. Use underscores if it improves readability (e.g. example_script.py is preferred, as opposed to examplescript.py or Example Script.py). I'll call mine my_first.py. You can save it wherever you want.
To stay organized, I recommend the following folder structure. Pick a location that you want to save all your scripts (e.g. your local home folder, /home/yourname in Linux, C:\Users\yourname\ on Windows, or a folder on a network drive that gets backed up).
Now create a new folder in that location named repos. Repos is short for Repositories, and this folder structure will be useful when we talk about git (in the future). Within repos create another folder named python-examples. The folder path will now look something like C:\Users\user\repos\python-examples. By the way, I will use the words folder and directory interchangeably.
Save or copy my_first.py into python-examples for now. Open my_first.py and copy-paste the following lines:
x = 1
y = 2
z = x + y
print(z)Save my_first.py.
my_first.pyOpen the command line. At this point, we can run my_first.py a couple of different ways.
The first option does not require us to change the command line to the python-examples directory. Type python with a space after it and drag my_first.py onto the command line. This will copy the full path to the file. If you hit enter, the code in my_first.py will run.
For the second option, we need to cd into the python-examples directory. If you don't know what that means, give it a quick google. After you cd into the same directory as my_first.py, you can simply type python my_first.py and hit enter.
The important takeaway is that python needs to know exactly where the file is located before it can run it. That means you can either tell it the absolute path of the file, OR you can move the command line to where the file is located and tell python the relative path to the file.
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