Python – Sort Matrix by Row Median

Given a Matrix, sort by median of each row.

Input : test_list = [[3, 4, 7], [1, 7, 2], [10, 2, 4], [8, 6, 5]] 
Output : [[1, 7, 2], [3, 4, 7], [10, 2, 4], [8, 6, 5]] 
Explanation : 2 < 3 < 4 < 6, sorted increasingly by median element.

Input : test_list = [[3, 4, 7], [1, 7, 2], [8, 6, 5]] 
Output : [[1, 7, 2], [3, 4, 7], [8, 6, 5]] 
Explanation : 2 < 3 < 6, sorted increasingly by median element. 

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

In this, we perform sort using sort() and median is computed using statistics function of computing median, median().

Python3

# Python3 code to demonstrate working of
# Sort Matrix by Row Median
# Using sort() + median()
from statistics import median

def med_comp(row):

    # computing median
    return median(row)

# initializing list
test_list = [[3, 4, 7], [1, 7, 2], [10, 2, 4], [8, 6, 5]]

# printing original list
print("The original list is : " + str(test_list))

# inplace sorting using sort()
test_list.sort(key = med_comp)

# printing result
print("Sorted Matrix : " + str(test_list))

Output

The original list is : [[3, 4, 7], [1, 7, 2], [10, 2, 4], [8, 6, 5]]
Sorted Matrix : [[1, 7, 2], [3, 4, 7], [10, 2, 4], [8, 6, 5]]

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

In this, we perform task of perform sort using sorted(), and lambda function is used as key function rather than external function. 

Python3

# Python3 code to demonstrate working of
# Sort Matrix by Row Median
# Using sorted() + lambda + median()
from statistics import median

# initializing list
test_list = [[3, 4, 7], [1, 7, 2], [10, 2, 4], [8, 6, 5]]

# printing original list
print("The original list is : " + str(test_list))

# inplace sorting using sort()
res = sorted(test_list, key = lambda row : median(row))

# printing result
print("Sorted Matrix : " + str(res))

Output

The original list is : [[3, 4, 7], [1, 7, 2], [10, 2, 4], [8, 6, 5]]
Sorted Matrix : [[1, 7, 2], [3, 4, 7], [10, 2, 4], [8, 6, 5]]