Python Program : List Method

Python Program : List Method

#list is a collection of diffrent types of data.

#enclosed with square brackets

#list elements seperated by comma

#It may be empty

#for creating a list we use list construtor or method

#list is mutable or changable (we can change / add/ remove / access list items)

# create an empty list

list1= []

print(list1)

#list with mixed data types

#with int string and float, tuple, list and set value.      

list2 = [1, "Hello", 3.4, (1,2,4), [1,3,4], {1,2,3}] 

print(list2)

#creating list with list constructor

tl= list(("apple", "banana", "cat"))

print(tl) #['apple', 'banana', 'cat']

#Acess list items

plang = ["Python", "Swift", "C++","Kotlin","C","C#"]

# access item at index 0

print(plang[0])# result:- Python

# access item at index 2

print(plang[2])   # C++

# access item at index 5

print(plang[5])   # C#

# access item at negative index -1

print(plang[-1])   # C#

# access item at negative index -2

print(plang[-2])   # C#

#access nested list element

list1=[5,3.2,'ram',6,8,9,[8,5,6]]

print(list1[6][1]) #5

#List slicing in Python

my_list = ['I','T','C','I',' ','H','A','R','D','O','I']

#items from index 2 to index 4

print(my_list[0:4]) #result- ['I','T','C','I']

# items from index 5 to end

print(my_list[5:]) #result:- ['H','A','R','D','O','I']

# result items beginning to end

print(my_list)

print(my_list[:])

print(my_list[:11])

print(my_list[-11:])

# Add element using append method in list

numbers= [21, 34, 54, 12]

print("Before Append:", numbers)

# after using append method

numbers.append(32) #it takes exactly one argument in one time

print("After Append:", numbers)

#with extend method you can add a list element in another list (join two lists)

#using extend method here you can also add any iterable object (tuples, sets, dictionaries etc.).

num1 = [2, 3, 5]

print("List1:", num1)

num2 = [4, 6, 8]

print("List2:", num2)

num2.extend(num1)

print("List after extend:", num2)

#or

fr_list = ["apple", "banana", "cherry"]

other_list = list(fr_list)

print(other_list)

#or using + concatenate operator

list1 = ["a", "b", "c"]

list2 = [1, 2, 3]

list3 = list1 + list2

print(list3)

#Creating nested list

list1 = [1, 2, 3, 4, 5]

print(list1)

list2 = [12, 13, 23]

print(list2)

list3 = [10, 20, 30]

print(list3)

NestedList = [list1, list2, list3, list4, list5]

print("The list of lists or Nested list is:")

print(NestedList)

#copy list items in another empty list

g= ["apple", "baby", "ambuj"]

a = g.copy()

print(a)

#or you can copy

g= ["anand", "vartika", "chaya"]

a = list(g)

print(a)

#insert an item in list without removing existing element

thislist = ["apple", "banana", "cow"]

thislist.insert(2, "water") 

print(thislist) # here result will be ["apple", "banana", "water","cow"]

# changing list item:(it's mutable so we can change list items.

color= ['pink', 'red', 'gray']

# changing the third item to 'C'

color[2] = 'green'

print(color)  # ['pink', 'red', 'green']

# changing the list items acc to range(change range)

th = ["apple", "blue", "cool", "orange", "kiwi", "mango"]

print(th) #["apple", "blue", "cool", "orange", "kiwi", "mango"]

th[1:3] = ["black", "bag"]

print(th) #["apple", "black", "bag", "orange", "kiwi", "mango"]

#pop method for using last element from list or remove item acor to index value

t = ["apple", "banana", "cherry"]

t.pop()

print(t) #["apple", "banana"]

t1=["ajay", "vijay", "chetan"]

t1.pop(2)

print(t1)

#remove method for remove any specific element

prog = ['Python', 'Swift', 'C++', 'C', 'Java', 'Ruby', 'php']

prog.remove('Java')

print(prog)

#remove list items using del keyword

prog = ['Python', 'Swift', 'C++', 'C', 'Java', 'Ruby', 'php']

# deleting the second item

del prog[1]

print(prog) # ['Python', 'C++', 'C', 'Java', 'Ruby', 'php']

# deleting the last item

del prog[-1]

print(prog) # ['Python', 'C++', 'C', 'Java', 'Ruby']

# delete first two items

del prog[0 : 2]  # ['C', 'Java', 'Ruby']

print(prog)

# del all list in one time with del and clear

prog = ['Python', 'Swift', 'C++', 'C', 'Java', 'Ruby', 'php']

del prog

prog1= ['Python', 'Swift', 'C++', 'C']

prog1.clear()

print(prog1) #return empty list

#creating a list with for loop

for i in range(6):

         print(i)

#print all items from list by using loop method

z=['a','b','c','d']

for i in (z):

    print(i)

#append item from one list to another list using loop

fruits = ["apple", "banana", "cherry", "kiwi", "mango"]

newlist = []

for x in fruits:

  if "a" in x:

    newlist.append(x)

print(newlist) #the result will be ["apple", "banana", "mango"] bcz a is found in all items

#sort the list items

fruit = ["orange", "mango", "kiwi", "pineapple", "banana"]

fruit.sort()

print(fruit) #['banana', 'kiwi', 'mango', 'orange', 'pineapple']

num= [100, 50, 65, 82, 23]

num.sort()

print(num)

#sort list in descending order

num= [100, 50, 65, 82, 23]

num.sort(reverse = True)

print(num)

#count the items from list

fruits = ["apple", "banana", "cherry","cherry"]

x = fruits.count("cherry")

print(x) #result:- 2

#find index value from list items

fruits = ['apple', 'banana', 'cherry']

x = fruits.index("banana")

print(x) #index value is 1