Python Cheat Sheet

Introduction

Python is a computer programming language often used to build websites and software, automate tasks, and conduct data analysis. Python is a general purpose language, meaning it can be used to create a variety of different programs and isn’t specialized for any specific problems. This versatility, along with its beginner-friendliness, has made it one of the most-used programming languages today. A survey conducted by industry analyst firm RedMonk found that it was the most popular programming language among developers in 2020. Python has many advantages.

Python is:

Easy to Read, Learn and Write
Improved Productivity
Interpreted Language
Dynamically Typed
Free and Open-Source

Variables

Variables are containers for storing data values. Python has no command for declaring a variable. A variable is created the moment you first assign a value to it.


          x = 5 

          y = "John" 

          print(x) 

          print(y)


          5 

          John

Declaring variables

Variables do not need to be declared with any particular type, and can even change type after they have been set.


        x = 69      # x is of type int 

        print(x) 

        x = "Sally" # x is now of type str 

        print(x)


          69 

          Sally

Data types

An attribute of data which tells the compiler or interpreter how the programmer intends to use the data.

Some Data types are:

Boolean
String
None
Int
Float

if else statements

Python supports the usual logical conditions from mathematics:

Equals: a == b
Not Equals: a != b
Less: a < b
Less than: a <= b

while and for loops

Loops are bit of code that run other code untill a condition is met

Python has two primitive loop commands:

while loops
for loops

The while loop

With the while loop we can execute a set of statements as long as a condition is true.

The for loop

A for loop is used for iterating over a sequence (that is either a list, a tuple, a dictionary, a set, or a string).

Loops can be exited using break.

Functions

In Python a function is defined using the def keyword:


          def my_function: 

            print("Hello from a function")

There are many great uses for functions. They can reduce repetition in code and make it easier to read