Beginners Python Cheat Sheet



  1. Python Cheat Sheet For Beginners
  2. Python Crash Course Cheat Sheet
  3. Beginners Python Cheat Sheet
  4. Basic Python Cheat Sheet

Beginner’s Python Cheat Sheet - Dictionaries Focuses on dictionaries: how to build and modify a dictionary, access the information in a dictionary, and loop through dictionaries in a variety of ways. Includes sections on nesting lists and dictionaries, using dictionary comprehensions, and more.

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  • Python is a multi-paradigm general-purpose, object-oriented programming language
  • It is a cross-platform programming language so code python file written in one system can be run same on different systems.
  • Easy to learn.
  • Simple Syntax and akin to pseudocode.
  • Automatic Garbage Collection.
  • It is an open-source programming language.

Applications of Python

Python is a very versatile language and it is used in many IT fields such as:

  • Web Development (back-end)
  • Desktop Applications
  • Data Science.
  • Machine Learning
  • Artificial Intelligence.

Major Characteristic of Python

  • Very Simple Programming language.
  • Python has the most libraries.
  • Support Object-Oriented programming
  • Ideal Programming language for a beginner.
  • Robust and Secure
  • Highly Scalable
  • Use Interpreter
  • Dynamic Programming language.
  • Multi-threading.

Python IDE’s

There are many IDE’s on the internet for Python the two most recommended ones are:

  • PyCharm (By Jetbrains)
  • Atom (Powered by GitHub)

Standard Data Types in Python:

Python has two types of Data types:

  • Base Type.
  • Container Type.
Beginners python cheat sheet free
Base Type
Data type NameData Type SyntaxSize
Integer Numberint14
Floating Point Numbersfloat16
Booleanbool14
stringstr26
bytesb’’21
Container Type Data Types
Data type NameData Type SyntaxExample
List (Ordered)list()[1,2,3] or list(range(1,4))
Tuple (Ordered)tuple()(1,2,3)
Dictionary (Unordered)dict(){0:1, 1:2, 2:3}
Set (unordered)set(){1,2,3}

Python Operators

Python has some standard operators which include arithmetic operators too.

Operator Name OperatorExample
Addition or concatenation+1+2

Or

“hello” + ”world”

Subtraction40 – 10 à 30
Multiplication*40 * 10 à 100

[0]*2 à[0,0]

division/10/5 à 2.0
Floor division//10 // 5 à2
Modules%10 % 5 à 0
Exponential**2**3 à 8

Python Comparison Operator

There are some operators in python which are used to compare two objects or values and return a Boolean value True and False:

Operator Name OperatorExample
Smaller than <2 < 3 èTrue
Greater than>3 > 2 èTrue
Smaller than and equal to<=2 <= 2 èTrue
Greater than and equal to>=3 >= 3 èTrue
Not equal to!=2 != 3èTrue
Equal to comparison2 2 èTrue
Python

Logical Operators

Python has three logical Operators:

  • and
  • or
  • not

Python Identifiers

Identifies are the name given to an object, identifiers can be also known as a variable name. There are some rules associated with an identifier or variable name. Using identifies we can give a name to variables, functions, modules, classes.

Identifiers rule:
  • The first letter of an identifier could be a lowercase or upper case Alphabet or _ (underscore symbol), and it could be followed by any alphabet, digit (0,9) and _.
  • There should be no special symbol in identifier except _.
  • Do not use reserved keywords as an identifier.

Variable Assignment

We use equal to “=” symbol to assign an object to an identifier.

The identifier name should be on the left side and value on the right side of the assignment operator.

Example:

x =20

Python AssignmentAssignment operatorExample
Simple and Single Assignment=x = 20
Assignment to same value=x = y = z =100
Multiple Assignment=x, y, z = 10, 20, 30
Swap values with Assignment operator=x, y = y, x
Unpacking sequence using assigmnet operator=x, *y = [20,10,30,70]
Assignment operator for increment+=x+=20
Assignment operator for Decrement-=x -=20

Python I/O

I/O methodsDescription
print()To print out the output
input()To take input from the user

Example:

By default input() accept value as string.

Type Conversion

Using there are many reserved keywords in python which are used to convert the data type of a variable.

Type Conversion Python SyntaxExample
Float to integer

Numeric string to integer

Boolean to integer

int()int(20.11)

int(“200”)

int(True)

Integer to float

Numeric string to float

Boolean to float

float()float(100)

float(“100”)

float(True)

Integer to string

float to string

Boolean to string

str()str(100)

str(100.00)

str(True)

ASSIC Code to characterchr()chr(64) à @
Character to ASSIC codeord()ord(‘@’) à 64
Convert a container data type and a string to a listlist()list(“Hello”)
Convert a container datatype to a dictdict()dict([(1,2), (2,3)])
Convert a container data type to a setset()set([1,2,3,4,5,5])

Indexing Calling in Python

Beginners_python_cheat_sheet_pcc_all.pdf

In python String, List and tuple objects support indexing calling.

Example:

Boolean Logic in Python

In python, we often encounter with Boolean values when we deal with comparison operator conditional statements.

Types of Boolean

In python there are two types of Booleans:

  • True
  • False
Boolean OperatorDescriptionExample
FalseIn python False, 0, empty container data type and None Treat as False value.bool(0) à False

bool([]) à False

bool({}) à False

bool(None) à False

TrueAnything except 0, None and empty data type in python considered as True Booleanbool(100) à True

Modules Name and Import

Use Syntax
Import the complete moduleimport module
Import complete modules with its all objectsfrom module import *
Import specific objects or class from a modulesfrom module import name_1, name_2
Import specific module and give a temporary namefrom module import name_1 as nam

Python Math Module

Math is the most important and widely used standard module of python, it provides many methods related to mathematics.

Math Module Example

from math import *

cos()cos(90)

-0.4480736161291701

sin()sin(200)

-0.8732972972139946

pi3.141592653589793
pow()pow(2,3) à 8.0
ceil()ceil(12.1) à13
floor()floor(12.9) à12
round()round(12.131,2) à12.13
abs()abs(-29) à 29

Conditional Statement

Python Conditional statement consists of 3 keywords if, elif and else.

Example:

Loops

There are two loops statements present in python:

  • for loop
  • while loop

Example:

Break

It is a statement used inside the loop statement, and it is used to terminate the loop flow and exist from the loop immediately.

Example:

Continue

Continue is the opposite of break, it is also used in loop statements and directly jump to the next iteration.

Example:

Function

To create a user-defined function in python we use the def keyword and to exit from a function we return a value using the return keyword.

Example:

Python List

A list is a collection of different data types, and it stores all elements in a contagious memory location.

Create a list

To create a list we use square brackets [ ].

Example:

Indexing

List support indexing, with the help of indexing we can access the specific element of the list.

Example:

List Slicing

With list slicing, we can access a sequence of elements present in the list.

Example:

List Unpacking
Loop through a List:
Adding Elements in the list:
Removing Elements from a list
If condition with a list
List Comprehension

lst_2 = [i for i in lst ]

Condition inside list comprehension
Zip function to combine two lists
Map and Filter on a list
List Operations
OperationsDescriptions
lst.append(val)Add items at the end
lst.extend(seq)Add sequence at the end
lst.insert(indx,val)Add value at a specific index
lst.remove(val)To delete the specific value from a list
lst.pop()To remove the last value from the list
Lst.sort()To sort the list

Python Tuples

Tuples in python similar to a list, the only difference is tuples are immutable.

Create a tuple:
Convert a list into a tuple
Indexing In tuple

Python Arrays

Python does not have inbuilt support for arrays but it has standard libraries to for array data structure. Array is a very useful tool to perform mathematical concepts.

Create an Array:

Python Sets

Python set is similar to the mathematic sets, a python set does not hold duplicates items and we can perform the basic set operation on set data types.

Create a Set:
Basic Set operation
Operations NameOperatorExample:
Union|s1 | s2
Intersection&s1 & s2
Differences1 – s2
Asymmetric Difference^s1 ^ s2

Dictionary

Dictionary is a collection of key: value pair and the key could only be an immutable data type.

Create a dictionary:

Python Cheat Sheet For Beginners

Convert a list into a dictionary:
Accessing Dictionary Elements

We use the key to access the corresponding value.

Looping Through a dictionary:

Generator Comprehension

Like a list comprehension, we have generator comprehension in generator comprehension we use parenthesis () instead of sq. brackets [].

Example:

Exception Handling:

In exception handling we deal with runtime error there are many keywords associated with exception handling:

keyword Description
tryNormal processing block
exceptError processing block
finallyFinal block executes for both tries or except.
raiseTo throw an error with a user-defined message.

Example:

Python Class

Class provides the Object-Oriented programming concepts to python.

Create a class
Create a constructor for a class:

The constructor is the special method of class which executes automatically during the object creation of the class.

Magic Methods of class
Magic methodsDescription
__str__()String representation of the object
__init__()Initialization or Constructor of the class
__add__()To override addition operator
__eq__()To override equal to method
__lt__()To override less than operator
Class Private members:

Conventionally to declare an attribute private we, write it name starting with __ double underscore.

Example:

Inheritance:

An inheritance we can use the methods and property of another class:

Example:

Multiple Inheritance:

Basic Generic Operations on Containers

Operators Description
len(lst)Items count
min(lst)To find the minimum item
max(lst)To find the maximum item
sorted(lst)List sorted copy
enumerate (c)Iterator on (index, item)
zip(lst_1,lst_2)Combine two list
all(c)If all items are True it returns True else false
any(c)True at least one item of c is true else false

People Also Read:

Data Science is rapidly becoming a vital discipline for all types of businesses. An ability to extract insight and meaning from a large pile of data is a skill set worth its weight in gold. Due to its versatility and ease of use, Python has become the programming language of choice for data scientists.

In this Python cheat sheet, we will walk you through a couple of examples using two of the most used data types: the list and the Pandas DataFrame. The list is self-explanatory; it’s a collection of values set in a one-dimensional array. A Pandas DataFrame is just like a tabular spreadsheet, it has data laid out in columns and rows.

Let’s take a look at a few neat things we can do with lists and DataFrames in Python!
Get the pdf here.

Python Cheat Sheet

Lists

Creating Lists

Create an empty list and use a for loop to append new values.

#add two to each value
my_list = []
for x in range(1,11):
my_list.append(x+2)

We can also do this in one step using list comprehensions:

my_list = [x + 2 for x in range(1,11)]

Creating Lists with Conditionals

As above, we will create a list, but now we will only add 2 to the value if it is even.

#add two, but only if x is even
my_list = []
for x in range(1,11):
if x % 2 0:
my_list.append(x+2)
else:
my_list.append(x)

Python Crash Course Cheat Sheet

Using a list comp:

my_list = [x+2 if x % 2 0 else x
for x in range(1,11)]

Selecting Elements and Basic Stats

Beginners Python Cheat Sheet

Select elements by index.

#get the first/last element
first_ele = my_list[0]
last_ele = my_list[-1]

Some basic stats on lists:

#get max/min/mean value
biggest_val = max(my_list)
smallest_val = min(my_list)avg_val = sum(my_list) / len(my_list)

DataFrames

Basic Python Cheat Sheet

Reading in Data to a DataFrame

We first need to import the pandas module.

import pandas as pd

Then we can read in data from csv or xlsx files:

df_from_csv = pd.read_csv(‘path/to/my_file.csv’,
sep=’,’,
nrows=10)
xlsx = pd.ExcelFile(‘path/to/excel_file.xlsx’)
df_from_xlsx = pd.read_excel(xlsx, ‘Sheet1’)

Slicing DataFrames

We can slice our DataFrame using conditionals.

df_filter = df[df[‘population’] > 1000000]
df_france = df[df[‘country’] ‘France’]

Sorting values by a column:

df.sort_values(by=’population’,
ascending=False)

Filling Missing Values

Let’s fill in any missing values with that column’s average value.

BeginnersCheat

df[‘population’] = df[‘population’].fillna(
value=df[‘population’].mean()
)

Applying Functions to Columns

Apply a custom function to every value in one of the DataFrame’s columns.

def fix_zipcode(x):
”’
make sure that zipcodes all have leading zeros
”’
return str(x).zfill(5)
df[‘clean_zip’] = df[‘zip code’].apply(fix_zipcode)