First Syntax#

Overview#

Let’s create a Python file and write code to print a message in the interpreter terminal:

  1. Open a text editor (integrated development environment - IDE) of your choice, and create a new file, called “first_code.py”. The .py extension is required for a Python file.

  2. In the new file, write the following code:

print("My first code!")

  1. Save the file.

  2. Open the anaconda terminal (or command prompt) and type:

> python first_code.py

and press Enter.

> "My first code!"

Congratulations, you have run a Python code!

Warning

If you got an error message, you will need to specify the python.exe location (e.g., “C:\Program Files\Anaconda\python.exe” in Windows OS). You should also check the “environmental variables” in Windows OS and add the python folder.

Conventions#

In these lectures we use the following conventions.

Commands in Anaconda command prompt are represented with >:

> cd change-to-my-folder
> python first_code.py

Codes in Python interpreter are represented with >>>:

>>> 2+2
>>> 10*213421

Code blocks written in IDE are:

123456

def my_function(input_message):
    """ printing message"""
    print(input_message)

Coding Style and PEP8#

PEP8 (Python Enhancement Proposal 8) is a set of guidelines and recommendations for writing Python code that promotes code readability, consistency, and maintainability. PEP 8 is widely accepted by the Python community. Here are three recommendations outlined in PEP 8:

  • Code Layout: PEP 8 suggests using 4 spaces for indentation and limiting line length to 79 characters. It also provides guidelines for using blank lines, spaces around operators, and consistent line breaks.

  • Naming Conventions: PEP 8 recommends using lowercase letters for variable and function names, separating words with underscores (snake_case). Class names should follow the CapWords convention. Constant variables should be written in uppercase letters with underscores.

  • Imports: PEP 8 recommends standard library imports first, followed by third-party library imports, and then local application or module imports. It also suggests avoiding wildcard imports (from module import *)