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Python Cheat Sheet for Beginners
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This cheatsheet contains basic concepts of python, I will be uploading advanced concepts of python in Part 2.
Table of Content
- Basics
- Arithmetic Operations
- Basic Data Types
- Taking User Input
- Strings
- Creating String
- String Concatenation
- String Replication
- Lists
- Combine Two List
- Nested List
- Sorting List
- Copy a List
- Tuples
- Convert Tuple to List
- Sets
- Creating a Set
- Set Operations
- Dictionaries
- Creating Dictionaries
- Dictionary Operations
- Conditional Statements
- If Statement
- Elif Statement
- Else Statement
- Loops
- While Loops
- For Loop
- Functions
- Creating a Function
- Calling Function
- Passing Arguments
- Lambda Functions
- ## This cheatsheet is still in progress
>>> 5 + 2 # Addition
7>>> 4 - 3 # Subtraction
1>>> 4 * 4 # Multiplication
16>>> 10 / 2 # Division
5.0 # Return float value
>>> 10 // 2 # Division, but return integer value
5>>> 10 % 2 # Modulas(Remainder)
0>>> 2 ** 3 # Exponenet(Power)
8| Data Type | Example |
|---|---|
| Integer | -2,-1,0,1,2 |
| Float | -1.5, -1.92, 2.25, 16.4 |
| String |
'python','is','love'
|
| Complex |
1j, 1+2j
|
| Boolean |
x = True, x = False
|
input() function is used to take input from the user.
name = input("Enter Your Name:")
print("Hello " + name)myString = "Python is easy!"A way to add two string together using "+" operator.
myString = "Python"
myString2 = "is easy"
ConString = myString + myString2
print(ConString)string = "Python" * 5
print(string)
# OUTPUT: PythonPythonPythonPythonPythonLists are used to store the multiple items in a single variable. List are created using square brackets.
List elements are changeable, can allow duplicate elements, and has defined order and that order will not change.Any new element will be placed at end of list. List index will start from 0 and will end at n-1 (where n is number of elements).
List elements are changeable, can allow duplicate elements, and has defined order and that order will not change.Any new element will be placed at end of list. List index will start from 0 and will end at n-1 (where n is number of elements).
Creating List
lst = ["python","cpp","java"]Fetching Values from List
>>> lst = ["python","cpp","java"]
>>> lst[0]
"python"
>>> lst[1]
"cpp"
>>> lst[2]
"java"Adding Items to List
lst = [1,2,3]
lst.append(4)
print(lst)
# OUTPUT : [1, 2, 3, 4]Method 2
insert() method is used to add item to specific index.
insert() method is used to add item to specific index.
lst = [1,3,4]
# SYNTAX : .insert(index number, element)
lst.insert(1,2)
print(lst)
# OUTPUT : [1,2,3,4]Removing Items from List
lst = [1,2,3,5]
lst.remove(5)
print(lst)
# OUTPUT : [1,2,3]lst1 = [1,2,3]
lst2 = ["x","y","z"]
combineList = lst1 + lst2
print(combineList)
# OUTPUT: [1, 2, 3, "x", "y", "z"]lst1 = [1,2,3]
lst2 = ["x","y","z"]
nestedList = [list1,list2]
print(nestedList)
# OUTPUT : [[1, 2, 3], ["x", "y", "z"]]lst = [123,51,214,23,56]
lst.sort()
print(lst)
#OUTPUT : [23, 51, 56, 123, 214]lst = ["a","b","c"]
lstcpy = lst.copy()
print(lstcpy)
# OUTPUT: ["a", "b", "c"]Tuples are similar to list. However, they are immutable and you can't change the values stored in a tuple. Tuple are created using round brackets.
Creating Tuple
myTuple = (1,2,3,4)
print(myTuple)Access Tuple Items
You can access tuple items by referring to the index number.
You can access tuple items by referring to the index number.
myTuple = (1,2,3,4)
print(myTuple[2])
# OUTPUT: 3Since Tuples are immutable. Instead we can convert tuple to list and can edit and then convert it back to tuple.
myTuple = (1,2,3)
convertedTuple = list(myTuple)
# Now we can edit the "convertedTuple" list.
convertedTuple[0] = 120
# Converting back to Tuple.
myTuple = tuple(ConvertedTuple)
print(myTuple)
# OUTPUT: (120,2,3)Sets are used to store multiple items in a single variable.
A Set is a collection which is both unordered and unindexed.
Sets are written with curly brackets.
Set cannot have two items with same value.
A set can contain different data types.
A Set is a collection which is both unordered and unindexed.
Sets are written with curly brackets.
Set cannot have two items with same value.
A set can contain different data types.
mySet = {"python", "java", "cpp"}
print(mySet)Set with Different Data Types
mySet = {"python",142,True,"abc"}Adding Element to Set
mySet = {1,2,3}
s.add(4)
print(s)
# OUTPUT: {1,2,3,4}Adding Multiple Elements to Set
mySet = {1,2,3}
mySet.update([4,5,6,7])
print(mySet)
# OUTPUT : {1,2,3,4,5,6,7}Dictionaries are used to store data in pairs.
A Pair contains key and value.
It is ordered,changeable and cannot contain duplicate values. If duplicate values found then it will overwrite the values.
A Pair contains key and value.
It is ordered,changeable and cannot contain duplicate values. If duplicate values found then it will overwrite the values.
# SYNTAX
# dictionary_name = {
# "key_name" : "Value",
# "key2_name" : "Value2"
# }
dict = {
"name" : "Van Rossum",
"ID" : 1234,
"year" : 1956
}Printing Items
print(dict["name"])Length of Dictionary
print(len(dict))
# OUTPUT : 2Adding Items
dict = {
"name" : "Van Rossum",
"ID" : 1234,
"year" : 1956
}
# Adding Item
dict["profession"] = "Programmer"Updating Item
# Syntax
# dict_name.update({"key":"value"})
dict.update({"ID":"9493"})Print All Items Values
for i in dict:
print(dict[i])
# OUTPUT:
# Van Rossum
# 9493
# 1956If statement contains a logical expressions using which data is compared and a decision is made.if expression:
statements or code
Note : Indentation is required in IF statement# Let's a create a program to check if person is eligible to vote or not
age = 15
if age < 18: # If age is less than 18 execute the block
print("Not Eligible to Vote")
if age >= 18: # If age is greater than or equal to 18 execute the block
print("Eligible to Vote")
# Here age is 15 so, 1st condition will be true and print the message.Elif keyword used if the previous if condition is false then it will execute the elif condition.# Let's take the same example but using elif condition
age = 20
if age < 18:
print("Not Eligible to Vote")
elif age >= 18:
print("Eligible to Vote")
#OUTPUT: Eligible to Voteelse keyword is used if all previous condition becomes false then it execute the else block.# Let us Understand using example of "If Number is +ve or -ve."
n = 0
if n > 0:
print("N is +ve")
elif n < 0:
print("N is -ve")
# In this case both the 'if' condition is false so we use 'else' block
else:
print("N is Zero")
# OUTPUT: N is ZeroLoops are used when we want to execute same thing repeatedly until condition is not satisfied. For example, If we want to print "Hello World" 100 times, we will write print statement 100 times. We will use loop to achieve this.
# print hello World 100 times
i = 1
while i <= 100:
print("Hello World")
i=i+1# Same example but using for loop
# for i in range(101)-> range function is used instead of "i<=100" from while loop
# Syntax for range() function -> range(n-1), So If n=100, range will only include 99.
for i in range(101):
print("Hello World")Learn More about Range() Function Here
Functions are block of code which only runs when it is called. Functions are defined using
def keyword. SYNTAX
def function_name():
code inside functiondef my_function():
print("Hello World")def greeting():
print("Good Morning")
# Calling Of Function
greeting()# let us understand using example
# -> Take username and greet
# passing name argument
def greet(name):
print("Hello " + name + ", Good Morning" )
greet("Rohan")
## Passing Two Arguments:
def greet(name, lastname):
print("Hello " + name + lastname + ", Good Morning" )
greet("Rohan", "Kiratsata")A lambda function is a small anonymous function means function without name.
SYNTAX
lambda arguments: expression# Lambda function to square of number
n = lambda x : x*x
print(n(5))This cheatsheet is written and managed by Rohan Kiratsata.
Something is missing? Contribute to this repo and improve.
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