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\___ \ / _ \ __| | | | '_ \
___) | __/ |_| |_| | |_) |
|____/ \___|\__|\__,_| .__/
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Good news! It's probably already installed! Run the following command in your CLI:
python3 --versionIf you get back something like Python 3.12.4 then you're all set.
If not, give one of these a go:
N.B. For learning, just install the latest version available. If you're on a project, bloody well use what they tell you to use!!
Don't you dare use IDLE, it's the "IDE" that bundled with Python but it's worse than worse, just don't subject yourself to it.
Pick VSCode or PyCharm.
- PyCharm hits the ground running but holds your hand to the point of getting clammy and it recently had a security vulnerability which threatened to expose all of your GitHub access tokens.
- VSCode just needs the
Python, andFlake8extensions installing and you're good to go (I prefer VSCode)
N.B. Just for this lesson, don't worry about how much flake8 tells you off. I don't want you to worry about errors like "blank line contains whitespace", "too many blank lines", "line too long (93 > 79 characters)", or "no newline at end of file".
This is all readability stuff and does not impact how the code runs. We'll go over it together in a future lesson but if you want to look it up yourself it all comes under the PEP8 standards.
So real quick, a venv is a virtual environment. It isolates your Python version and installed libraries from other projects and more importantly - your base Python installation. If you install libraries against your base Python version, other projects will need to account for having that library installed when they install dependencies, this will break a lot of stuff.
To create a venv called "my-cool-venv" (assuming you have Python installed now), you run:
python3 -m venv my-cool-venvTo activate the "my-cool-venv" venv, you run:
source ./my-cool-venv/bin/activate....unless you're on bloody Windows!!
Then you have to run:
my-cool-venv\Scripts\activate
If you are on Windows, I totally recommend using WSL by the way. It puts a little Linux right inside your machine which is just beautiful <3
Pick one from PyPI here, let's say you picked pandas.
With your venv active, run:
pip install pandasor whatever library you're installing. Again, we'll add professionalism to this later.
| WARNING |
|---|
| Make sure you ONLY ever install libraries onto a venv. Installing libraries without use of a venv will absolutely knacker your setup. But we'll talk more next lesson |
Beyond what you install on your venv, there's an absolute tonne of included libraries. Check out my favorites for newcomers
To import (and then use) a library, say json, you'd do this:
import json
my_json_string = json.dumps(some_python_dictionary)Imports can be done anywhere in your code, but traditionally they're done at the top of the file.
So, you never ever import multiple libraries on one line like this:
import json, pprintThis makes broken libraries and modules a pain to get figured out. So you do this:
import json
import pprintYou can also alias a library if you get sick of writing out the full name every time:
import json as js
js.dumps(some_python_dictionary)If you don't want all of a library, you can import just little bits of it. So, instead of this:
import time
print("Hold on...")
time.sleep(1)
print("The epoch time is:")
print(time.time())You can do this:
from time import time, sleep
print("Hold on...")
sleep(1)
print("The epoch time is:")
print(time())In this situation, we're only importing one module on the one line so it's allowed, but you can break that import across multiple lines if you like:
from time import (
time,
sleep,
)
print("Hold on...")
sleep(1)
print("The epoch time is:")
print(time())You can even alias the individual items you're importing from that module/library:
from time import (
time,
sleep as zzz,
)
print("Hold on...")
zzz(1)
print("The epoch time is:")
print(time())Just slap some code in a .py file (e.g. my_code.py) and then pass the filepath into the python3 command.
e.g. python3 my_code.py
If you've got your venv active then you can just give the command python my_code.py without specifying python3
Don't worry too much about whether you're doing it right for this lesson, as long as you get some code running that's what matters. I just want you playing around and getting to grips with the basics today, we'll bring professionalism into it later.
You can type code in directly against the interpreter in the REPL (Read Evaluate Print Loop). To do so, just type python3 (or simply python with a venv active).
This can be a little tricky as it doesn't really have code-completion or suggestions.
N.B. To exit the interpreter give it the command exit() (as keyboard interrupts won't work)
The interpreter will print out anything returned by an expression or function, as well as what is supposed to be printed to the console.
There are many many ways to set up your Python environment. I only suggest the above as what I consider to be that with the fewest headaches. But please do take a look around at what else is on offer, you may very commonly hear of PyEnv, Poetry, and Anaconda.
If you are only just getting started in Python, forget about those... then remember them much much later and look into them then.
Nothing. That's all you're getting at this point, we're just keen to get a thin base going to build on top of.