Python

list.append(x) # append x to end of list list.extend(iterable) # append all elements of iterable to list list.insert(i, x) # insert x at index i list.remove(x) # remove first occurance of x from list list.pop([i]) # pop element at index i (defaults to end of list) list.clear() # delete all elements from the list list.index(x[, start[, end]]) # return index of element x list.count(x) # return number of occurances of x in list list.reverse() # reverse elements of list in-place (no return) list.sort(key=None, reverse=False) # sort list in-place list.copy() # return a shallow copy of the list

## Python has a set of built-in methods that you can use on lists. append() # Adds an element at the end of the list clear() # Removes all the elements from the list copy() # Returns a copy of the list count() # Returns the number of elements with the specified value extend() # Add the elements of a list (or any iterable), to the end of the current list index() # Returns the index of the first element with the specified value insert() # Adds an element at the specified position pop() # Removes the element at the specified position remove() # Removes the item with the specified value reverse() # Reverses the order of the list sort() # Sorts the list ## Happy coding :)

# example of list in python myList = [9, 'hello', 2, 'python'] print(myList[0]) # output --> 9 print(myList[-3]) # output --> hello print(myList[:3]) # output --> [9, 'hello', 2] print(myList) # output --> [9, 'hello', 2, 'python']

# Planet list #twitter ----------->: @MasudHanif_ # Happy Coding.. planet = ["Mercury","Venus","Earth","Mars","Jupiter","Saturn","Uranus","Neptune"] for planets in planet: print(f"{planets} from solar system")

fruits = ['orange', 'apple', 'pear', 'banana', 'kiwi', 'apple', 'banana'] fruits.count('apple') # count number of apples found in list # output 2 fruits.count('tangerine') # count number of tangerines in list # output 0 fruits.index('banana') # find the first index of banana # output 3 fruits.index('banana', 4) # Find next banana starting a position 4 # output 6 fruits.reverse() # reverse fruits array fruits # output ['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange'] fruits.append('grape') # append grape at the end of array fruits # output ['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange', 'grape'] fruits.sort() fruits # output ['apple', 'apple', 'banana', 'banana', 'grape', 'kiwi', 'orange', 'pear'] len(fruits) # length of fruits array # output 8 # loop and print each fruit for fruit in fruits: print(fruit)

list.append() list.clear() list.copy() list.count() list.extend() list.index() list.insert() list.pop() list.remove() list.append() list.clear() list.copy() list.count() list.extend() list.index() list.insert() list.pop() list.remove() list.sort() list(sorted(list)) list(reverse(x)) # x=string, tuple, range, list

my_list = [1, 2, '3', True]# We assume this list won't mutate for each example below len(my_list) # 4 my_list.index('3') # 2 my_list.count(2) # 1 --> count how many times 2 appears my_list[3] # True my_list[1:] # [2, '3', True] my_list[:1] # [1] my_list[-1] # True my_list[::1] # [1, 2, '3', True] my_list[::-1] # [True, '3', 2, 1] my_list[0:3:2] # [1, '3'] # : is called slicing and has the format [ start : end : step ]

#Creating lists my_list = [1, "Hello", 3.4, 0, "World"] my_nested_list = [['Hello', 'World'],[47,39]] #Accessing lists my_list[1] # Hello my_list[-2] # 0 my_list[:3] # [1, "Hello", 3.4] my_nested_list[1] #[47,39] my_nested_list[0][1] # World

txt = "this is a wild string"

print(txt.replace("i", "x"))  # print string with all i characters replaced with x
print(txt.replace("i", "x", 2))  # print string with first two i characters found with x
print(txt.upper())  # print string in all uppercase letters
print(txt.lower())  # print string in all uppercase letters

print(ord('A'))  # print the ordinal value of a character
print(chr(95))  # print character from its ordinal value
print('Yes' * 5) # print string Yes 5 times

# Reference strings by index
print(txt[0])  # print first letter of string from starting index
print(txt[0:2])  # print first two letters from starting index
print(txt[1:])  # print all characters except the first letter
print(txt[0::2])  # print every second character
print(txt[::-1])  # print string in reverse
print(txt[-1])  # print the last character in a string
print(txt[-2:])  # print the last who characters in a string

# check if a wild is found in txt
if "wild" in txt:
  print("wild is found in txt")

# check if a blah is not found in txt
if "blah" not in txt:
  print("is not found in txt")

# Check if txt starts with this
if txt.startswith("this"):
  print("Starts with this")

# check if txt ends with ing
if txt.endswith("ing"):
  print("Ends with ing")

# Split a string into a tuple when the delimiter is first encountered
txt = 'random-data'

data_split = txt.partition('-')
print(data_split)
# output ('random', '-', 'data')

len(txt)  # Return length of string

# loop through each character in string
for char in txt:
  print(char)

# Display price with commas and 2 digit precision
price = 9749000
display_price = f"My price {price:,.2f}"
print(display_price)


fruits = ['orange', 'apple', 'pear', 'banana', 'kiwi', 'apple', 'banana']
fruits.count('apple')  # count number of apples found in list
# output 2
fruits.count('tangerine')  # count number of tangerines in list
# output 0
fruits.index('banana')  # find the first index of banana
# output 3
fruits.index('banana', 4)  # Find next banana starting a position 4
# output 6
fruits.reverse()  # reverse fruits array
fruits
# output ['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange']
fruits.append('grape')  # append grape at the end of array
fruits
# output ['banana', 'apple', 'kiwi', 'banana', 'pear', 'apple', 'orange', 'grape']
fruits.sort()
fruits
# output ['apple', 'apple', 'banana', 'banana', 'grape', 'kiwi', 'orange', 'pear']

len(fruits)  # length of fruits array
# output 8

# loop and print each fruit
for fruit in fruits:
  print(fruit)
  
empty_set = set()

basket = {'apple', 'orange', 'apple', 'pear', 'orange', 'banana'}
print(basket)                      # show that duplicates have been removed
# output {'orange', 'banana', 'pear', 'apple'}

# check if orange is in basket set
print('orange' in basket)
# output true

# convert a string to a set of letters - sets contains no duplicates
set_a = set('abcd')
set_b = set('bcde')

# the operations below returns new sets
# print letters in set_a but not in set_b - difference
print(set_a - set_b)
# output {'a'}

# print set letters that is in either set a or b - union
print(set_a | set_b)
# output {'a', 'c', 'e', 'b', 'd'}

# print letters that are in both set_a and set_b - intersection
print(set_a & set_b)
# output {'c', 'd', 'b'}

# print letters that are in set_a and set_b when the letters are found in a set but no the other set - symmetric_difference()
print(set_a ^ set_b)
# output {'a', 'e'}

# Creating dictionaries
dict1 = {'color': 'blue', 'shape': 'square', 'volume': 40}
dict2 = {'color': 'red', 'edges': 4, 'perimeter': 15}

# Creating new pairs and updating old ones
dict1['area'] = 25  # {'color': 'blue', 'shape': 'square', 'volume': 40, 'area': 25}
dict2['perimeter'] = 20  # {'color': 'red', 'edges': 4, 'perimeter': 20}

# Accessing values through keys - an KeyError will occur if the key does not exists
print(dict1['shape'])

# You can also use get, which doesn't cause an exception when the key is not found
dict1.get('false_key')  # returns None
dict1.get('false_key', "key not found")  # returns the custom message that you wrote

# Delete item key and return the value if the key does not exists a KeyError occurs
print(dict1.pop('volume'))

# Merging two dictionaries
dict1.update(dict2)  # if a key exists in both, it takes the value of the second dict
dict1  # {'color': 'red', 'shape': 'square', 'area': 25, 'edges': 4, 'perimeter': 20}

# Getting only the values, keys or both (can be used in loops)
dict1.values()  # dict_values(['red', 'square', 25, 4, 20])
dict1.keys()  # dict_keys(['color', 'shape', 'area', 'edges', 'perimeter'])
dict1.items()
# dict_items([('color', 'red'), ('shape', 'square'), ('area', 25), ('edges', 4), ('perimeter', 20)])

# create a shallow copy of dict1
dict3 = dict1.copy()
# dict3 = {'color': 'red', 'shape': 'square', 'area': 25, 'edges': 4, 'perimeter': 20}

# empty list print(list()) # vowel string vowel_string = 'aeiou' print(list(vowel_string)) # vowel tuple vowel_tuple = ('a', 'e', 'i', 'o', 'u') print(list(vowel_tuple)) # vowel list vowel_list = ['a', 'e', 'i', 'o', 'u'] print(list(vowel_list))

list1 = [10, 20, 4, 45, 99] mx=max(list1[0],list1[1]) secondmax=min(list1[0],list1[1]) n =len(list1) for i in range(2,n): if list1[i]>mx: secondmax=mx mx=list1[i] elif list1[i]>secondmax and mx != list1[i]: secondmax=list1[i] print("Second highest number is : ", str(secondmax)) Output:- Second highest number is : 45

mylist = [] # creating an empty list # appending values entered by user to list for i in range(5): print("Enter value of n[", i, "]") mylist.append(input()) # printing final list print(mylist)

# Python program to demonstrate # Creation of List # Creating a List List = [] print("Blank List: ") print(List) # Creating a List of numbers List = [10, 20, 14] print(" List of numbers: ") print(List) # Creating a List of strings and accessing # using index List = ["Geeks", "For", "Geeks"] print(" List Items: ") print(List[0]) print(List[2]) # Creating a Multi-Dimensional List # (By Nesting a list inside a List) List = [['Geeks', 'For'], ['Geeks']] print(" Multi-Dimensional List: ") print(List)

# empty list print(list()) # output: [] # vowel string vowel_string = 'aeiou' print(list(vowel_string)) #output: ['a', 'e', 'i', 'o', 'u'] # vowel tuple vowel_tuple = ('a', 'e', 'i', 'o', 'u') print(list(vowel_tuple)) #output: ['a', 'e', 'i', 'o', 'u'] # vowel list vowel_list = ['a', 'e', 'i', 'o', 'u'] print(list(vowel_list)) #output: ['a', 'e', 'i', 'o', 'u']