The Ultimate Python Cheatsheet

The Ultimate Python Cheatsheet

The Ultimate Python CheatSheet

Basics Basic syntax from the python programming language

Showing Output To User the print function is used to display or print output

print("Content that you wanna print on screen")

Taking Input From User the input function is used to take input from the user

var1 = input("Enter your name: ")

Empty List This method allows you to create an empty list

my_list = []

Empty Dictionary By putting two curly braces, you can create a blank dictionary

my_dict = {}

Range Function range function returns a sequence of numbers, eg, numbers starting from 0 to n-1 for range(0, n)


Comments Comments are used to make the code more understandable for programmers, and they are not executed by compiler or interpreter.

Single line comment

#This is a single line comment

Multi-line comment

'''This is a

Escape Sequence An escape sequence is a sequence of characters; it doesn't represent itself when used inside string literal or character.

Newline Newline Character


Backslash It adds a backslash


Single Quote It adds a single quotation mark


Tab It gives a tab space


Backspace It adds a backspace


Octal value It represents the value of an octal number


Hex value It represents the value of a hex number


Carriage Return Carriage return or \r is a unique feature of Python. \r will just work as you have shifted your cursor to the beginning of the string or line.


Strings Python string is a sequence of characters, and each character can be individually accessed. Using its index.

String You can create Strings by enclosing text in both forms of quotes - single quotes or double-quotes.

variable_name = "String Data"

Slicing Slicing refers to obtaining a sub-string from the given string.

var_name[n : m]

String Methods isalnum() method Returns True if all characters in the string are alphanumeric


isalpha() method Returns True if all characters in the string are alphabet


isdecimal() method Returns True if all characters in the string are decimals


isdigit() method Returns True if all characters in the string are digits


islower() method Returns True if all characters in the string are lower case


isspace() method Returns True if all characters in the string are whitespaces


isupper() method Returns True if all characters in the string are upper case


lower() method Converts a string into lower case


upper() method Converts a string into upper case


strip() method It removes leading and trailing spaces in the string


List A List in Python represents a list of comma-separated values of any data type between square brackets.


var_name = [element1, element2, and so on]

List Methods index method Returns the index of the first element with the specified value


append method Adds an element at the end of the list


extend method Add the elements of a list (or any iterable) to the end of the current list


insert method Adds an element at the specified position

list.insert(position, element)

pop method Removes the element at the specified position and returns it


remove method The remove( ) method removes the first occurrence of a given item from the list


clear method Removes all the elements from the list


count method Returns the number of elements with the specified value


reverse method Reverse the order of the list


sort method Sorts the list


Tuples Tuples are represented as a list of comma-separated values of any data type within parentheses.

Tuple Creation

variable_name = (element1, element2, ...)

Tuple Methods count method It returns the number of times a specified value occurs in a tuple


index method It searches the tuple for a specified value and returns the position.


Sets A set is a collection of multiple values which is both unordered and unindexed. It is written in curly brackets.

Set Creation: Way 1

var_name = {element1, element2, ...}

Set Creation: Way 2

var_name = set([element1, element2, ...])

Set Methods: add() method Adds an element to a set


clear() method Remove all elements from a set


discard() method Removes the specified item from the set


intersection() method Returns intersection of two or more sets

set.intersection(set1, set2 ... etc)

issubset() method Checks if a Set is Subset of Another Set


pop() method Removes an element from the set


remove() method Removes the specified element from the Set


union() method Returns the union of Sets

set.union(set1, set2...)

Dictionaries The dictionary is an unordered set of comma-separated key: value pairs, within {}, with the requirement that within a dictionary, no two keys can be the same.


<dictionary-name> = {<key>: value, <key>: value ...}

Adding Element to a dictionary By this method, one can add new elements to the dictionary

<dictionary>[<key>] = <value>

Updating Element in a dictionary If the specified key already exists, then its value will get updated

<dictionary>[<key>] = <value>

Deleting Element from a dictionary del let to delete specified key: value pair from the dictionary

del <dictionary>[<key>]

Dictionary Functions & Methods len() method It returns the length of the dictionary, i.e., the count of elements (key: value pairs) in the dictionary


clear() method Removes all the elements from the dictionary


get() method Returns the value of the specified key


items() method Returns a list containing a tuple for each key-value pair


keys() method Returns a list containing the dictionary's keys


values() method Returns a list of all the values in the dictionary


update() method Updates the dictionary with the specified key-value pairs


Conditional Statements The if statements are the conditional statements in Python, and these implement selection constructs (decision constructs).

if Statement

if(conditional expression):

if-else Statement

if(conditional expression):

if-elif Statement

if (conditional expression) :
elif (conditional expression) :
else :

Nested if-else Statement

if (conditional expression):
if (conditional expression):

Iterative Statements An iteration statement, or loop, repeatedly executes a statement, known as the loop body, until the controlling expression is false (0).

For Loop The for loop of Python is designed to process the items of any sequence, such as a list or a string, one by one.

for <variable> in <sequence>:

While Loop A while loop is a conditional loop that will repeat the instructions within itself as long as a conditional remains true.

while <logical-expression> :

Break Statement The break statement enables a program to skip over a part of the code. A break statement terminates the very loop it lies within.

for <var> in <sequence> :
if <condition> :

Continue Statement The continue statement skips the rest of the loop statements and causes the next iteration to occur.

for <var> in <sequence> :
if <condition> :

Functions A function is a block of code that performs a specific task. You can pass parameters into a function. It helps us to make our code more organized and manageable.

Function Definition

def my_function(parameters):
# Statements

File Handling File handling refers to reading or writing data from files. Python provides some functions that allow us to manipulate data in the files.

open() function

var_name = open("file name", "opening mode")

close() function


Read () function The read functions contains different methods, read(),readline() and readlines()

read() #return one big string

It returns a list of lines


It returns one line at a time


Write () function This function writes a sequence of strings to the file.

write () #Used to write a fixed sequence of characters to a file

It is used to write a list of strings


Append () function The append function is used to append to the file instead of overwriting it. To append to an existing file, simply open the file in append mode (a):

file = open("Hello.txt", "a")

Exception Handling An exception is an unusual condition that results in an interruption in the flow of the program.

try and except A basic try-catch block in python. When the try block throws an error, the control goes to the except block.

[Statement body block]
raise Exception()
except Exception as e:
[Error processing block]

OOPS It is a programming approach that primarily focuses on using objects and classes. The objects can be any real-world entities.

class The syntax for writing a class in python

class class_name:

class with a constructor The syntax for writing a class with the constructor in python

class Abhiraj:

# Default constructor
def __init__(self): = "Abhiraj"

# A method for printing data members
def print_me(self):

object Instantiating an object

<object-name> = <class-name>(<arguments>)

filter function The filter function allows you to process an iterable and extract those items that satisfy a given condition

filter(function, iterable)

issubclass function Used to find whether a class is a subclass of a given class (classinfo) or not

issubclass(class, classinfo)

Iterators and Generators Here are some of the advanced topics of the Python programming language like iterators and generators

Iterator Used to create an iterator over an iterable

iter_list = iter(['Harry', 'Aakash', 'Rohan']) 

Generator Used to generate values on the fly

# A simple generator function
def my_gen():
n = 1
print('This is printed first')
# Generator function contains yield statements
yield n
n += 1
print('This is printed second')
yield n
n += 1
print('This is printed at last')
yield n

Decorators Decorators are used to modifying the behavior of function or class. They are usually called before the definition of a function you want to decorate.

property Decorator (getter)

def name(self):
return self.__name

setter Decorator It is used to set the property 'name'

def name(self, value):

Deletor Decorator It is used to delete the property 'name'

@name.deleter #property-name.deleter decorator
def name(self, value):
del self.__name

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