As we have already known some basics of the list and accessing an element from it. Now today here we are going to learn insertion of a new element in the list, update element from the list which is already available, and delete items from the list.
There are different ways to insert an element in the list
1. append()
2. insert()
3. extend()
append() method add an element to the end of the list.
Syntax:
Lstname.append(element)
#element:any type of variable string,number, etc.. Example:
color=['black','red']
#now append 'green' to list color
color.append("green")
#now print list
print(color)
#Result:['black','red','green']Output:
['black','red','green']
Example:
#initilize two list
color=['black','red']
color2=['brown','green']
color.append(color2)
print(color)Output:
['black','red',['brown','green']]
You can not append more than one element at a time using append
This is wrong example:
#initilize list
color=['black','red']
#Try to Append Two element at time
color.append('brown','green') Output Error:
TypeError: append() takes exactly one argument (2 given)
- append() method is used for appending an element to the end of the list to overcome from this problem use the insert() method to insert an element at a given particular location.
- insert() method inserts the specified value at the specified position.
- if you inserting a new element at 1 index position and if one element already present at 1 index position then the old item position will be right-shifted by one index.
Syntax:
listname.insert(position,element) Both position and element are required element
position: an integer number specifying the position where to insert an item.
element: an element of any data type string, number, list, etc...
Example:
#initilize list
color=['black','red','brown']
#insert 'green' element at 1 st position
color.insert(1, 'green')
#print the new list
print(color)Output:
['black','green','red','brown']
- while inserting element if you have given a positive integer index which is not present in the current list then the item will automatically be added at last position.
Example:
num=[1,3,4,7]
#insert 8 element at 10th position
num.insert(10,8)
print(num) Output:
[1,3,4,7,8]
you can also use the negative index for inserting element
- similarly, if you have give negative index which is not present in the current list the item will be added at 0th index
Example:
#initialize num list
num=[1,3,4,7]
#insert 8 element at -10th position
num.insert(-10,8)
print(num) Output:
[8,1,3,4,7]
extend() method add the number of list element to the end of the current list
Syntax:
list1.extend(lst2) Example:
#initilize two list
num1=[1,3,4,7]
num2=[8, 9]
#add num2 list to num1
num1.extend(num2)
print(num1) Output:
[1,3,4,7,8, 9]
There are different ways to delete elements from the list.
1. del
2. pop()
3. remove()
if you removed the item using del statement you cant use them for further process.
Syntax:
del list or element position- if you pass the list to the del statement then the list will completely be removed from the stack.
Example:
#initilize list
number=[1,3,4,7,8, 9]
#Delete 4 from above list
del number[2]
#print updated list
print(number) Output:
[1, 3, 7, 8, 9]
#initilize list
number=[1,3,4,7,8, 9]
#delete total list
del number
print(number) Output:
#Result:error because number list is deleted
#ERROR:name 'number' is not defined
- pop() method remove element from given position.
- pop() method remove the element from specified position and return the deleted element value.
Syntax
listname.pop(position) Example:
#initilize list
number=[1,3,4,7,8, 9]
#remove 8 element which present 4 or -2 index
del_val=number.pop(4)
print(number)
print(del_val)Output:
[1, 3, 4, 7, 9]
8
- if you give out of range index for pop() method then it will generate an error saying list item out of range...
Example
number=[1,3,4,7,8, 9]
number.pop(100) Output:
#Result:error will occured. pop index out of range
- remove() method remove the first occurence of of given value.
- we can not save result of remove() method
Syntax;
listname.remove(value) Example:
#initilize list
color=['red', 'green', 'blue']
#Remove "green " From list
color.remove("green")
#print remaining list
print(color) Output:
['red', 'blue']
- If you trying to remove XYZ element from the list and that element is not present in the list python will generate error "x is not in the list".
Example:
#initilize list
color=['red', 'green', 'blue']
#remove "black" From above list
color.remove("black")Output:
Error - x is not in the list
For updating the element value
Syntax:
list[index]="new value"Example:
#initilize list
color=["blue","green","red"]
#update blue with *black*
color[0]="black"
#print new updated list
print(color) output:
["black","green","red"]
- If you provide out of range index while updating value then it will generate out of range index error