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Python program to Sort Matrix by Maximum Row element
  • Last Updated : 11 Oct, 2020

Given a Matrix, sort rows by maximum element.

Input : test_list = [[5, 7, 8], [9, 10, 3], 
[10, 18, 3], [0, 3, 5]] 
Output : [[10, 18, 3], [9, 10, 3], [5, 7, 8], [0, 3, 5]] 
Explanation : 18, 10, 8 and 5 are maximum elements in rows, hence sorted.
Input : test_list = [[9, 10, 3], 
[10, 18, 3], [0, 3, 5]] 
Output : [[10, 18, 3], [9, 10, 3], [0, 3, 5]] 
Explanation : 18, 10, and 5 are maximum elements in rows, hence sorted. 
 

Method #1 : Using sort() + max()

In this, we perform task of sorting using sort() with key being maximum element from each row. The reverse keyword is used to sort by keeping maximum element rows at start and decreasing from there.

Python3




# Python3 code to demonstrate working of 
# Sort Matrix by Maximum Row element
# Using sort() + max()
  
def max_sort(row):
    return max(row)
  
# initializing list
test_list = [[5, 7, 8], [9, 10, 3],
             [10, 18, 3], [0, 3, 5]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# sort() for sorting, max to get maximum values
test_list.sort(key = max_sort, reverse = True)
  
# printing result 
print("The maximum sorted Matrix : " + str(test_list))

Output:



The original list is : [[5, 7, 8], [9, 10, 3], [10, 18, 3], [0, 3, 5]]
The maximum sorted Matrix : [[10, 18, 3], [9, 10, 3], [5, 7, 8], [0, 3, 5]]

Method #2 : Using sorted() + lambda + max()

In this, we perform task of sorting using sorted() for non-inplace sort, and lambda function is used instead of external function to include maximum element from row logic.

Python3




# Python3 code to demonstrate working of 
# Sort Matrix by Maximum Row element
# Using sorted() + lambda + max()
  
# initializing list
test_list = [[5, 7, 8], [9, 10, 3],
             [10, 18, 3], [0, 3, 5]]
  
# printing original list
print("The original list is : " + str(test_list))
  
# sorted() for sorting, max to get maximum values
# reverse for reversed order
res = sorted(test_list, key = lambda row : max(row), reverse=True)
  
# printing result 
print("The maximum sorted Matrix : " + str(res))

Output:

The original list is : [[5, 7, 8], [9, 10, 3], [10, 18, 3], [0, 3, 5]]
The maximum sorted Matrix : [[10, 18, 3], [9, 10, 3], [5, 7, 8], [0, 3, 5]]

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