Python List methods
Python List Methods are the built-in methods in lists used to perform operations on Python lists/arrays.
Below, we’ve explained all the Python list methods you can use with Python lists, for example, append(), copy(), insert(), and more.
List Methods in Python
Let’s look at some different list methods in Python for Python lists:
| S.no | Method | Description |
|---|---|---|
| 1 | append() | Used for adding elements to the end of the List. |
| 2 | copy() | It returns a shallow copy of a list |
| 3 | clear() | This method is used for removing all items from the list. |
| 4 | count() | These methods count the elements. |
| 5 | extend() | Adds each element of an iterable to the end of the List |
| 6 | index() | Returns the lowest index where the element appears. |
| 7 | insert() | Inserts a given element at a given index in a list. |
| 8 | pop() | Removes and returns the last value from the List or the given index value. |
| 9 | remove() | Removes a given object from the List. |
| 10 | reverse() | Reverses objects of the List in place. |
| 11 | sort() | Sort a List in ascending, descending, or user-defined order |
| 12 | min() | Calculates the minimum of all the elements of the List |
| 13 | max() | Calculates the maximum of all the elements of the List |
This article is an extension of the below articles:
- List Methods in Python | Set 1 (in, not in, len(), min(), max()…)
- List Methods in Python | Set 2 (del, remove(), sort(), insert(), pop(), extend()…)
Adding Element in List in Python
Let’s look at some built-in list functions in Python to add element in a list.
1. Python append() Method
Adds element to the end of a list.
Syntax: list.append (element)
Example:
# Adds List Element as value of List.
List = ['Mathematics', 'chemistry', 1997, 2000]
List.append(20544)
print(List)
Output
['Mathematics', 'chemistry', 1997, 2000, 20544]
2. Python insert() Method
Inserts an element at the specified position.
Syntax:
list.insert(<position, element)
Note: The position mentioned should be within the range of List, as in this case between 0 and 4, else wise would throw IndexError.
Example:
List = ['Mathematics', 'chemistry', 1997, 2000]
# Insert at index 2 value 10087
List.insert(2, 10087)
print(List)
Output
['Mathematics', 'chemistry', 10087, 1997, 2000]
3. Python extend() Method
Adds items of an iterable(list, array, string , etc.) to the end of a list.
Syntax: List1.extend(List2)
Example:
List1 = [1, 2, 3]
List2 = [2, 3, 4, 5]
# Add List2 to List1
List1.extend(List2)
print(List1)
# Add List1 to List2 now
List2.extend(List1)
print(List2)
Output
[1, 2, 3, 2, 3, 4, 5] [2, 3, 4, 5, 1, 2, 3, 2, 3, 4, 5]
Important Functions of the Python List
We have mentioned some essential Python list functions along with their syntax and example:
1. Python sum() Method
Calculates the sum of all the elements of the List.
Syntax: sum(List)
Example:
List = [1, 2, 3, 4, 5]
print(sum(List))
Output
15
What happens if a numeric value is not used as a parameter?
The sum is calculated only for numeric values, else wise throws TypeError.
See example:
List = ['gfg', 'abc', 3]
print(sum(List))
Output:
Traceback (most recent call last):
File "", line 1, in
sum(List)
TypeError: unsupported operand type(s) for +: 'int' and 'str'
2. Python count() Method
Calculates the total occurrence of a given element of the List.
Syntax: List.count(element)
Example:
List = [1, 2, 3, 1, 2, 1, 2, 3, 2, 1]
print(List.count(1))
Output
4
3. Python len() Method
Calculates the total length of the List.
Syntax: len(list_name)
Example:
List = [1, 2, 3, 1, 2, 1, 2, 3, 2, 1]
print(len(List))
Output
10
4. Python index() Method
Returns the index of the first occurrence. The start and end indexes are not necessary parameters.
Syntax: List.index(element[,start[,end]])
Example:
List = [1, 2, 3, 1, 2, 1, 2, 3, 2, 1]
print(List.index(2))
Output
1
Another example:
In this example, we are using index() method which is one of the list functions in Python, searching the first occurrence of the element 2, starting from index 2 in the list.
List = [1, 2, 3, 1, 2, 1, 2, 3, 2, 1]
print(List.index(2, 2))
Output
4
5. Python min() Method
Calculates minimum of all the elements of List.
Syntax: min(iterable, *iterables[, key])
Example:
numbers = [5, 2, 8, 1, 9]
print(min(numbers))
Output
1
6. Python max() Method
Calculates the maximum of all the elements of the List.
Syntax: max(iterable, *iterables[, key])
Example:
numbers = [5, 2, 8, 1, 9]
print(max(numbers))
Output
9
7. Python sort() Method
Sort the given data structure (both tuple and list) in ascending order.
Key and reverse_flag are not necessary parameter and reverse_flag is set to False if nothing is passed through sorted().
Syntax: list.sort([key,[Reverse_flag]])
Example:
List = [2.3, 4.445, 3, 5.33, 1.054, 2.5]
#Reverse flag is set True
List.sort(reverse=True)
#List.sort().reverse(), reverses the sorted list
print(List)
Output
[5.33, 4.445, 3, 2.5, 2.3, 1.054]
8. Python reverse() Method
reverse() function reverses the order of list.
Syntax: list. reverse()
Example:
# creating a list
list = [1,2,3,4,5]
#reversing the list
list.reverse()
#printing the list
print(list)
Output
[5, 4, 3, 2, 1]
Deletion of List Elements
To Delete one or more elements, i.e. remove an element, many built-in Python list functions can be used, such as pop() and remove() and keywords such as del.
1. Python pop() Method
Removes an item from a specific index in a list.
Syntax: list.pop([index])
The index is not a necessary parameter, if not mentioned takes the last index.
Note: The index must be in the range of the List, elsewise IndexErrors occur.
Example 1:
List = [2.3, 4.445, 3, 5.33, 1.054, 2.5]
print(List.pop())
Output
2.5
Example 2:
List = [2.3, 4.445, 3, 5.33, 1.054, 2.5]
print(List.pop(0))
Output
2.3
2. Python del() Method
Deletes an element from the list using it’s index.
Syntax: del list.[index]
Example:
List = [2.3, 4.445, 3, 5.33, 1.054, 2.5]
del List[0]
print(List)
Output
[4.445, 3, 5.33, 1.054, 2.5]
3. Python remove() Method
Removes a specific element using it’s value/name.
Syntax: list.remove(element)
Example :
List = [2.3, 4.445, 3, 5.33, 1.054, 2.5]
List.remove(3)
print(List)
Output
[2.3, 4.445, 5.33, 1.054, 2.5]
We have discussed all major Python list functions, that one should know to work on list. We have seen how to add and remove elements from list and also perform basic operations like count , sort, reverse using list Python Methods.
Hope these Python methods were of help!
