Python CheatSheet

Python is an interpreted high-level general-purpose programming language. Its design philosophy emphasizes code readability with its use of significant indentation. Its language constructs as well as its object-oriented approach aim to help programmers write clear, logical code for small and large-scale projects.

Python is dynamically-typed and garbage-collected. It supports multiple programming paradigms, including structured (particularly, procedural), object-oriented and functional programming. It is often described as a "batteries included" language due to its comprehensive standard library.

Python is a popular programming language. It was created by Guido van Rossum, and released in 1991.

It is used for:

• web development (server-side).
• software development.
• mathematics.
• system scripting.

yourAge = 26      # yourAge variable now is of type int
yourName = "William Jack" # yourName variable now is now of type str
print(name)
# Result: William Jack

yourMsg = "Hello, Wellcome to bestforstudy !"
print(yourMsg[2:5])
# Result: llo

yourList = []
yourList.append(1) # Your list now is List int
yourList.append(2) # Your list now is List int

# Print out the list
for item in mylist:
    print(item)
# Result: 1
# Result: 2

number = 500
if number > 100:
    print("number is greater than 100")
else:
    print("number is not greater than 100")
# Result: number is greater than 100

for item in range(100):
    if item == 50: 
        break
    print(item)
else:
    print("Finish loop !!")

def yourFunction():
    print("This is inside your function")

# execute function
yourFunction()
# Result: This is inside your function

with open("yourFile.txt", "r", encoding='utf8') as file:
    for line in file:
        print(line)

# yourFile.txt: this is path where your file locate
# encoding: is encoding when handle your file. At here, it is utf-8 encoding

result = 15 + 35 # => 50
result = 45 - 15 # => 30
result = 50 * 10  # => 500
result = 16 / 4  # => 4.0 (Float Division)
result = 16 // 4 # => 4 (Integer Division)
result = 25 % 2  # => 1
result = 5 ** 3  # => 125

# this way
counterNumber = 5
counterNumber += 15 # Result: 20

# Equal to this way
counterNumber = 5
counterNumber = counterNumber + 15  # Result: 20

# Plus Equals with String
message = "Welcome to "
message += "bestforstudy.com"
# Result: Welcome to bestforstudy.com

yourWebsite = 'bestforstudy.com'
f"Hello, Welcome to {website}"
# Result: "Hello, Welcome to bestforstudy.com"

num = 100
f'{num} + 10 = {num + 10}'
# Result: '10 + 10 = 20'

message = "First way to declare a String"
message = 'Another way to declare a String'

multilineString = """First way to declare multiple line String,
Hello everyone,
This is an example !!!"""

multilineString = '''First way to declare multiple line String,
Hello everyone,
This is an example !!!'''

x = 10    # int type
y = 5.9  # float type
z = 3j   # complex type

print(type(x))
# Result: class 'int'

yourBool = True 
yourBool = False

bool(0)     # Result: False
bool(1)     # Result True

yourList1 = ["tank", "car", "plan"]
yourList2 = [True, False, False]
yorList3 = [1, 2, 6, 9, 0]
yourList4 = list((4, 6, 8, 7,3, 0))

yourTuple = (3, 5, 7)
yourTuple = tuple((3, 5, 7))

yourSet1 = {"a", "b", "c", "d", "e"}   
yourSet2 = set(("a", "b", "c", "d", "e"))

# Empty Dict
your_empty_dict = {}

a = {"one": 1, "two": 2, "three": 3}
a["one"]
# Result: 1

# Your dict key
a.keys()
your_dict_keys(['one', 'two', 'three'])

# Your dict value
a.values()
your_dict_values([1, 2, 3])

# Add a key:val to dict
a.update({"four": 4})
a.keys()

# Your Result after add key:val
your_dict_keys(['one', 'two', 'three', 'four'])
a['four']
# Result: 4

# Integers
x = int(10)  # value of x is 10
y = int(1.5) # value of y is 1
z = int("30") # value of z is 30

# Floats
x = float(11)     # value of x is 11.0
y = float(2.9)   # value of y is 2.9
z = float("2")   # value of z is 2.0
w = float("5.2") # value of w is 5.2

# Strings
x = str("string1") # value of x is 'string1'
y = str(200)    # value of y is '200'
z = str(2.0)  # value of z is '2.0'

yourString = "Hello, Wellcome to bestforstudy.com"

print(yourString[1])
# Result: e

print(yourString[-1])
# Result: m

for char in "HelloWorld":
   print(char)
#Result: 
H
e
l
l
o
W
o
r
l
d

yourString = "bestforstudy.com"
print(len(yourString))
# Result: 18

yourString = '===+'
n = 8
yourString * n

# Result:
'===+===+===+===+===+===+===+===+'

yourFullString = "bestforstudy.com"
yourSubString = "cheatsheet"

if yourSubString in yourFullString:
    print("Your String Found!")
else:
    print("Your String Not found!")

# Result: Your String Found!

# First way
str1="Hello"
str2="World"
str=str1+str2
print(str)
# Result: HelloWorld

# Second way
str1="Hello"
str1=str1*3
print("Concatenated same string:",str1)

# First way
name = "William"
print("Hello, %s!" % name)
# Result: Hello William!

name = "Yasuo"
age = 29
print("%s is %d years old." % (name, age))
# Result: Yasuo is 29 years old.

# Second way using format() method
txt1 = "My name is {fname}, I'm {age}".format(fname = "William", age = 40)
txt2 = "My name is {0}, I'm {1}".format("John",15)
txt3 = "My name is {}, I'm {}".format("John",30)

yourName = input("Please, Enter your name: ")
>>> Please, Enter your name: Rec
name
'Rec'

yourString = ",".join(["Banana", "Apple", "Orange"])
print(yourSring)

# Result: Banana,Apple,Orange

"bestforstudy.com".endswith(".com")
# Result: True

New in version 3.6.

A formatted string literal or f-string is a string literal that is prefixed with 'f' or 'F'. These strings may contain replacement fields, which are expressions delimited by curly braces {}. While other string literals always have a constant value, formatted strings are really expressions evaluated at run time.

myWebsite = 'bestforstudy.com'
print(f"Hello, {myWebsite}")
# Result: "Hello, bestforstudy.com"

num = 1num = 100
f'{num} + 10 = {num + 10}'
# Result: '10 + 10 = 20'

f"""She said {"I'm Jess"}"""
# Result: "She said I'm Jess"

f'5 {"{stars}"}'
# Result: '5 {stars}'
f'{{5}} {"stars"}'
# Result: '{5} stars'

name = 'Jhin'
age = 30
f"""Hello!
     I'm {name}.
     I'm {age}."""
# Result: "Hello!\n    I'm Jhin.\n    I'm 30."

# [width]
f'{"width":11}'
# Result: 'width       '

# fill left
f'{"left":*>10}'   
# Result: '******left'

# fill right
f'{"right":*<10}'   
# Result: 'right******'

# fill center
f'{"center":*^10}'   
'***center***'

# fill with numbers
f'{12345:0>10}'    
# Result: '0000012345'

# binary type
f'{10:b}'        
# Result: '1010'

# octal type
f'{10:o}'        
# Result: '12'

# hexadecimal type
f'{200:x}'       
# Result: 'c8'

f'{200:X}'
# Result: 'C8'

# scientific notation
f'{345600000000:e}' 
# Result: '3.456000e+11'

# character type
f'{65:c}'       
# Result: 'A'

# [type] with notation (base)
f'{10:#b}'      
# Result: '0b1010'

f'{10:#o}'
# Result: '0o12'

f'{10:#x}'
# Result: '0xa'

# negative numbers
f'{-13579:0=10}'  
# Result: '-000013579'

# [0] shortcut (no align)
f'{13579:010}'    
# Result: '0000013579'

f'{-13579:010}'
# Result: '-000012345'

# [.precision]
import math       
math.pi
# Result: 3.141592653589793

f'{math.pi:.2f}'
# Result: '3.14'

# [grouping_option]
f'{4000000:,.2f}' 
# Result: '4,000,000.00'

f'{5000000:_.2f}'
# Result: '5_000_000.00'

# percentage
f'{0.25:0%}'      
# Result: '25.000000%'

f'{0.25:.0%}'
# Result: '25%'

# [sign] (+/-)
f'{13579:+}'      
# Result: '+13579'

f'{-13579:+}'
# Result: '-13579'

f'{-13579:+10}'
# Result: '    -13579'

f'{-13579:+010}'
# result: '-000013579'

list1 = []
print(list1)
# Result: []

list2 = [4, 5, 6]
print(list2)
# Result: [4, 5, 6]

list3 = list((1, 2, 3))
print(list3)
# Result: [1, 2, 3]

list4 = list(range(1, 11))
print(list4)
# Result: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Lists are used to store multiple items in a single variable.

Lists are one of 4 built-in data types in Python used to store collections of data, the other 3 are Tuple, Set, and Dictionary, all with different qualities and usage.

• List is a collection which is ordered and changeable. Allows duplicate members.
• Tuple is a collection which is ordered and unchangeable. Allows duplicate members.
• Set is a collection which is unordered, unchangeable*, and unindexed. No duplicate members.
• Dictionary is a collection which is ordered** and changeable. No duplicate members.

# First way to generate list with condition
list(filter(lambda x : x % 2 == 1, range(1, 20)))
# Result: [1, 3, 5, 7, 9, 11, 13, 15, 17, 19]

# Second way to generate list with condition
list(filter(lambda x: x > 6, [3, 4, 5, 6, 7, 8, 9, 10]))
# Result: [7, 8, 9, 10]

# Third way to generate list with condition
[x ** 2 for x in range (1, 11) if  x % 2 == 1]
# Result: [1, 9, 25, 49, 81]

# Final way to generate list with condition
[x for x in [3, 4, 5, 6, 7, 8, 9, 10] if x > 6]
# Result: [7, 8, 9, 10]

# Empty list
li = []

li.append(10)
print(li)
# Result: [10]

li.append(20)
print(li)
# Result: [10, 20]

li.append(4)
print(li)
# Result: [10, 20, 4]

li.append(30)
print(li)
# Result: [10, 20, 4, 30]

li = ['a', 'b', 'c']
print(li.pop())
# Result: 'c'

print(li)
# Result: ['a', 'b']

del li[0]
print(li)
# Result: ['b']

li = ['apple', 'banana', 'coconut', 'durian']

# Get first value
print(li[0])
'apple'

# Get last value
li[-1]
print('durian')

# This will raise error
print(li[4])
# Traceback (most recent call last): 
# File "<stdin>", line 1, in <module>
# IndexError: list index out of range

# First way
yourList = [10, 30, 50]
yourList.extend([90, 11, 13])
print(yourList)
# Result: [10, 30, 50, 90, 11, 13]

# Second way
yourList = [10, 30, 50]
yourList + [90, 11, 13]
# Result: [10, 30, 50, 90, 11, 13]

# Define a list
li = [3, 1, 3, 2, 5]
print(li.count(3))
# Result: 2

li = ['abc'] * 3
print(li)
['abc', 'abc', 'abc']

# Define a list
li = [35, 15, 36, 23, 50]
li.sort()
print(li)
# Result: [15, 23, 35, 36, 50]

li.reverse()
print(li)
# Result: [50, 36, 35, 23, 15]

# Syntax of list slicing:
a_list[start:end]
a_list[start:end:step]

# Slicing
a = ['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster']
a[2:5]
['bacon', 'tomato', 'ham']
a[-5:-2]
['egg', 'bacon', 'tomato']
a[1:4]
['egg', 'bacon', 'tomato']


# Omitting index
a[:4]
['spam', 'egg', 'bacon', 'tomato']
a[0:4]
['spam', 'egg', 'bacon', 'tomato']
a[2:]
['bacon', 'tomato', 'ham', 'lobster']
a[2:len(a)]
['bacon', 'tomato', 'ham', 'lobster']
a
['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster']
a[:]
['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster']


# With a stride
['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster']
a[0:6:2]
['spam', 'bacon', 'ham']
a[1:6:2]
['egg', 'tomato', 'lobster']
a[6:0:-2]
['lobster', 'tomato', 'egg']
a
['spam', 'egg', 'bacon', 'tomato', 'ham', 'lobster']
a[::-1]
['lobster', 'ham', 'tomato', 'bacon', 'egg', 'spam']

number = 15
if number > 12:
    print("number is bigger than 10.")
elif num < 12:
    print("number is smaller than 10.")
else:
    print("num is equal 12.")
# Result: number is bigger than 10.

numberA = 330
numberB = 200
result = "numberA" if numberA > numberB else "numberB"
print(result)
# Result: numberA

value = True
if not value:
    print("Value is False")
elif value is None:
    print("Value is None")
else:
    print("Value is True")

numberArr = [1, 2, 3, 4, 5, 6, 7]
for number in numberArr:
    print(number)
# Result: 1, 2, 3, 4, 5, 6, 7

sports = ["swimming", "football", "baseball"]
for i, value in enumerate(sports):
    print(i, value)

number = 0
while number < 10:
    # Write your logic here ....
    print(number)
    number += 1  # Shorthand for number = number + 1

for letter in 'Python':     
   if letter == 'h':
      break
   print 'Current Letter :', letter

# Result: 
# Current Letter : P
# Current Letter : y
# Current Letter : t

for i in range(9):
  if i == 3:
    continue
  print(i)
# Result: 0, 1, 2, 4, 5, 6, 7, 8

for i in range(4):
    print(i) 
# Result: 0 1 2 3

for i in range(4, 8):
    print(i) 
# Result: 4 5 6 7

for i in range(4, 10, 2):
    print(i) 
# Result: 4 6 8

yourName = ['Harry', 'Petter', 'Alex']
age = [14, 35, 25]
for n, a in zip(name, age):
    print('%s is %d years old' %(n, a))
# Result: 
# Harry is 14 years old
# Petter is 35 years old
# Alex is 25 years old

result = [x**2 for x in range(10) if x % 2 == 0]
 
print(result)
# [0, 4, 16, 36, 64]

def basicFunc():  
    print('Hello, Wellcome to bestforstudy.com!')

def addFunc(x, y):
    print("x is %s, y is %s" %(x, y))
    return x + y

addFunc(10, 25)    
# Result: 35

def varargs(*args):
    return args

varargs(1, 2, 3)  
# Result: (1, 2, 3)

def keyword_args(**kwargs):
    return kwargs

keyword_args(big="foot", loch="ness")
# Result {"big": "foot", "loch": "ness"}

def swap(x, y):
    return y, x

x = 1
y = 2
x, y = swap(x, y)  
# Result: x = 2, y = 1

def add(x, y=10):
    return x + y

add(5)      
# Result: 15

add(5, 20)  
# Result: 25

(lambda x: x > 2)(3)
# Result: True

(lambda x, y: x ** 2 + y ** 2)(2, 1)
# Result: 5

import math

print(math.sqrt(16))  
# Result: 4.0

from math import ceil, floor

print(ceil(3.7))   
# Result: 4.0

print(floor(3.7))  
# Result: 3.0

from functions import *

print(cube(3))

import math as m

math.sqrt(16) == m.sqrt(16)
# Result: True

import math

dir(math)