Python Program To Sort a list of tuples by second Item
In this, tutorial We have one list of tuples in, and we need to sort it by the index of sorting, which is the second component of the tuple. When a list of tuples is sorted by the second value, the tuples' positions in the list are rearranged so that the second values of the tuples are in ascending order.
So, We are going to sort a list of tuples with the help of three methods. Let us have a look at the examples to understand the inputoutput format:
Input List = [('shubh', 2), ('sinha', 4), ('tonight', 8), ('study', 6)]
Outpt List = [('shubh', 2), ('sinha', 4), ('study', 6), ('tonight', 8)]
Input List = [(200, 6), (100, 3), (400, 12), (300, 9)]
Output List = [(100, 3), (200, 6), (300, 9), (400, 12)]
To execute this task, we can follow multiple approaches, some are discussed below:

Using sort() method

Using sorted() method

Using binary search method
We will discuss all these approaches in detail separately.
Approach 1: Using sort() method
Python has various builtin sorting functions. When utilizing the sorting techniques, we must provide a method that swaps the element to the second member of the tuple.
Algorithm
 Initialize Tuple List.
 Define the function Sort(For Sorting Tuple)
 Set the key to sorting using the second element
 Use sublist lambda
 Print the result
Program
In this program, the actual content of the tuple is changed while sorting with this method. The sort() function uses the default comparisons operator between items to sort the components of a list in ascending or descending order. Instead of using the default operator, use the key argument to give the function name to be used for comparison.
#tuple list
tuple = [(200, 6), (100, 3), (400, 12), (300, 9)]
print("Orignal Tuple List :" ,tuple)
#function
def Sort(tuple):
# Sorts in Ascending order
tuple.sort(key = lambda a: a[1])
return tuple
# printing the sorted list of tuples
print("Sorted Tuple List:" ,Sort(tuple))
Orignal Tuple List : [('shubh', 2), ('sinha', 4), ('tonight', 8), ('study', 6)]
Sorted Tuple List: [('shubh', 2), ('sinha', 4), ('study', 6), ('tonight', 8)]
Approach 2: Using sorted() functions
The Sorted() function sorts a list and always returns a list with sorted entries, without changing the original order. In this program, we will use a sorted function similar to a sort function but this function comes with three parameters i.e., Iterable, keys, and reverse. Let us have a look at the algorithm followed by code:
Algorithm
 Initializing List
 Print the original List
 Define the function Sort(For Sorting Tuple)
 Set the key to sorting using the second element
 Use sublist lambda
 Print the result
Program
The sorted() method returns a sorted list of the iterable object that was passed in. You may choose whether to sort the results in ascending or descending order. Numbers are ordered numerically, whereas strings are arranged alphabetically.
# Tuple
tuple = [(200, 6), (100, 3), (400, 12), (300, 9)]
print("Orignal List: ", tuple)
# Function to sort
def Sort(tuple):
# reverse = None (Sorts in Ascending order)
return(sorted(tuple, key = lambda a: a[1]))
# sorted list of tuples
print("Sorted List: ", Sort(tuple))
Orignal List: [(200, 6), (100, 3), (400, 12), (300, 9)]
Sorted List: [(100, 3), (200, 6), (300, 9), (400, 12)]
Approach 3: Using Binary Search Operation
We have a list of tuples in our program, and we need to sort it by the index of sorting, which is the second item in the tuple. We'll effectively utilize a sorting method, except instead of utilizing the list's first value, we'll use the tuple's second member.
Algorithm
 Initializing List
 Print the original List
 Define the length of the tuple list
 Sorting using binary function
 Print the result
Program
In this program, sorting is done using the binary sorting approach. The second member of the tuple will be used as an index for sorting the list.
# Creating a new tuple
tuple = [('shubh', 2), ('sinha', 4), ('tonight', 8), ('study', 6)]
print("Orignal list : ", str(tuple))
# Sorting the list of tuples using second item
Len = len(tuple)
for i in range(0, Len):
for j in range(0, (Len  i  1)):
if(tuple[j][1] > tuple[j+1][1]):
temp = tuple[j]
tuple[j] = tuple[j+1]
tuple[j+1] = temp
# sorted list
print("Sorted List : ", str(tuple))
Orignal list : [('shubh', 2), ('sinha', 4), ('tonight', 8), ('study', 6)]
Sorted List : [('shubh', 2), ('sinha', 4), ('study', 6), ('tonight', 8)]
Conclusion
In this tutorial, we have seen two approaches to sort a list of tuples by the second Item. The first approach is by using the sort() method which sorts a list and always returns a list with sorted entries, without changing the original order and the second approach is by using a sorted method which is similar to the sort method and the last method is by using the binary search method in which we have a list of tuples in our program, and we need to sort it by the index of sorting, which is the second item in the tuple.