Python | Find most common element in each column in a 2D list

Given a 2D list, write a Python program to find the most common element in each column of the 2D list.

Examples:

Input : [[1, 1, 3],
        [2, 3, 3],
        [3, 2, 2],
        [2, 1, 3]]
Output : [2, 1, 3]

Input : [['y', 'y'],
         ['y', 'x'],
         ['x', 'x']]
Output : ['y', 'x']

Method #1 : Using most_common() from collections module

most_common() return a list of the n most common elements and their counts from the most common to the least. Thus, we can easily find the most common elements in each column using list comprehension.

# Python3 program to find most common
# element in each column in a 2D list
from collections import Counter

def mostCommon(lst):

    return [Counter(col).most_common(1)[0][0] for col in zip(*lst)]

# Driver code
lst = [[1, 1, 3],
       [2, 3, 3],
       [3, 2, 2],
       [2, 1, 3]]
print(mostCommon(lst))

Output:

[2, 1, 3]

Method #3 : Using mode() from statistics module

# Python3 program to find most common
# element in each column in a 2D list
from scipy.stats import mode
import numpy as np

def mostCommon(lst):

    val, count = mode(lst, axis = 0)
    return val.ravel().tolist()

# Driver code
lst = [[1, 1, 3],
       [2, 3, 3],
       [3, 2, 2],
       [2, 1, 3]]
print(mostCommon(lst))

Output:

[2, 1, 3]