What is List:
- a built-in data structure available in Python
- a list of comma-separated values (items) between square brackets.
- It can contain heterogeneous values such as integers, floats, strings, tuples, lists, and dictionaries.
- Python lists are mutable; yes, they can change
- a = [ 1, 342, 2233423, ‘India’, ‘Fedora’]
- It works as a sequence
- Ex : a[0] result=>1
How to create a list:
- Creating a list
Syntax: <variable_name>= []
Example : List1 = []
Creating a list with value
Trainers= [‘yogesh’, ‘sharma’, ‘vikas’]
Slicing the list
<list_name>[start : stop : step]
Trainers[1:3]
Trainers[:4]
list1 = [1,2,3,4,5,6,7,8,9,10,11,12,13]
Operation: list1[1:13:3]
Result: [2, 5, 8, 11]
Deleting values from a list
- By using the del keyword, you can delete a value or a slice of list from the list.
C_W_team = [‘hulk’, ‘iron-man’, ‘Captain-America’, ‘Thor’,”Vision”]
del C_W_team[0]
C_W_team [‘iron-man’, ‘Captain-America’, ‘Thor’, ‘Vision‘]
Unpacking List Values
- a,b = [10,20]
- You can assign a list value to variables by using the assignment operator.
List Operations:
- Updating the list:Lists are mutable, so the values of a list can be updated.
Syntax : ListName[index]=new_value
- Addition of Python lists:You can add two lists by using the + operator
Syntax : List3 = List1+List2
- Multiplication of lists :By using the * operator, you can perform multiplication of Python lists
syntax: List2 = List1*2
- in operator:You can use the in operator on list with the if statement
- Syntax: if ‘value’ in list:
- statement-1
List Functions:
- len() :The len() function returns the number of elements or values in the list
- max () :The max (list) function returns the element of the list with the maximum value.
- min () : The min () function returns an element from the Python list with the minimum value.
- sorted () : return list with sorted item.
List Methods:
- append () : Syntax: list.append ()
The method adds a value at the end of the list.
- extend (): list1.extend (seq) .
- Count():The count () method is used to find the occurrence of an item in a list.
- index () :The index () method is used to find the index of a particular item in a list.
- insert():Insert an item into list
–Syntax: list1.insert (index1, item)
- remove(): Remove an item from list.
list.remove(item)
- Pop(): The pop () method removes and returns the last item from the list.
list.pop()
l=[1,2,'yogesh']
del l[1]
print(l)
# Unpacking of List
a,b=[10,20]
print(a)
# Updating List Item
l[1]='vikas'
print(l)
# Output : [1, 'vikas']
#Updating List: Create New List
l2 = ['harsh',1]
l3 = l+l2
print(l3)
# Output : [1, 'vikas', 'harsh', 1]
# Multiplication of lists
l4 = l2*2
print(l4)
# Output : ['harsh', 1, 'harsh', 1]
#in operator
if 'harsh' in l2:
print('harsh is available in list')
# Output : harsh is available in list
# max function
listmax = [1,2,34,23,45,108,27]
print(max(listmax))
# Output : 108
# Min Function
print(min(listmax))
# Output : 1
# Sorted:
print(sorted(listmax))
# Output : [1, 2, 23, 27, 34, 45, 108]
# Len
print(len(listmax))
# Output : 7
# Append- Only one item at a time
listmax2=['hi','hellp']
listmax.append(listmax2)
print(listmax)
# Output:[1, 2, 34, 23, 45, 108, 27, ['hi', 'hellp']]
# Extend Example
listmax.extend(listmax2)
print(listmax)
#Output : [1, 2, 34, 23, 45, 108, 27, ['hi', 'hellp'], 'hi', 'hellp']
# Count Function
print(listmax.count(1))
# Output =1
# Index Method
newlist=['hi','hello','yogeshdotnet']
print(newlist.index('hello'))
# Output = 1
# Insert Method
newlist.insert(1,'bye')
print(newlist)
# Output : ['hi', 'bye', 'hello', 'yogeshdotnet']
# Remove Item.
newlist.remove('bye')
print(newlist)
# Output : ['hi', 'hello', 'yogeshdotnet']
print(newlist.pop())
# Output: yogeshdotnet
print(newlist)
# Output : ['hi', 'hello']