Python – Reverse Row sort in Lists of List

Last Updated : 14 May, 2020

Sometimes, while working with data, we can have a problem in which we need to perform the sorting of rows of matrix in descending order. This kind of problem has its application in web development and Data Science domain. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using loop + sort() + reverse
This problem can be solved using a loop to loop over each row. The sort and reverse can be used to perform reverse sort of rows.

# Python3 code to demonstrate 
# Reverse Row sort in Lists of List
# using loop
  
# initializing list 
test_list = [[4, 1, 6], [7, 8], [4, 10, 8]]
  
# printing original list
print ("The original list is : " + str(test_list))
  
# Reverse Row sort in Lists of List
# using loop
for ele in test_list: 
    ele.sort(reverse = True) 
  
# printing result 
print ("The reverse sorted Matrix is : " + str(test_list))

Output :

The original list is : [[4, 1, 6], [7, 8], [4, 10, 8]]
The reverse sorted Matrix is : [[6, 4, 1], [8, 7], [10, 8, 4]]

Method #2 : Using list comprehension + sorted()
This is yet another way in which this task can be performed. In this, we perform in similar way, just pack the logic in one line using list comprehension to provide a compact alternative.

# Python3 code to demonstrate 
# Reverse Row sort in Lists of List
# using list comprehension + sorted()
  
# initializing list 
test_list = [[4, 1, 6], [7, 8], [4, 10, 8]]
  
# printing original list
print ("The original list is : " + str(test_list))
  
# Reverse Row sort in Lists of List
# using list comprehension + sorted()
res = [sorted(sub, reverse = True) for sub in test_list]
  
# printing result 
print ("The reverse sorted Matrix is : " + str(res))

Output :

The original list is : [[4, 1, 6], [7, 8], [4, 10, 8]]
The reverse sorted Matrix is : [[6, 4, 1], [8, 7], [10, 8, 4]]

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Python – Reverse Row sort in Lists of List