# Python – Count the frequency of matrix row length

• Last Updated : 27 Mar, 2021

Given a Matrix, the task is to write a Python program to get the count frequency of its rows lengths.

Input : test_list = [[6, 3, 1], [8, 9], [2], [10, 12, 7], [4, 11]]

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Output : {3: 2, 2: 2, 1: 1}

Explanation : 2 lists of length 3 are present, 2 lists of size 2 and 1 of 1 length is present.

Input : test_list = [[6, 3, 1], [8, 9], [10, 12, 7], [4, 11]]

Output : {3: 2, 2: 2}

Explanation : 2 lists of length 3 are present, 2 lists of size 2.

Method #1 : Using dictionary + loop

In this we check for each row length, if length has occurred in the memorize dictionary, then the result is incremented or if a new size occurs, the element is registered as new.

## Python3

 # Python3 code to demonstrate working of# Row lengths counts# Using dictionary + loop  # initializing listtest_list = [[6, 3, 1], [8, 9], [2],              [10, 12, 7], [4, 11]]  # printing original listprint("The original list is : " + str(test_list))  res = dict()for sub in test_list:      # initializing incase of new length    if len(sub) not in res:        res[len(sub)] = 1      # increment in case of length present    else:        res[len(sub)] += 1  # printing resultprint("Row length frequencies : " + str(res))

Output:

The original list is : [[6, 3, 1], [8, 9], [2], [10, 12, 7], [4, 11]]
Row length frequencies : {3: 2, 2: 2, 1: 1}

Method #2 : Using Counter() + map() + len()

In this, map() and len() get the lengths of each sublist in the matrix, Counter is used to keep the frequency of each of the lengths.

## Python3

 # Python3 code to demonstrate working of# Row lengths counts# Using Counter() + map() + len()from collections import Counter  # initializing listtest_list = [[6, 3, 1], [8, 9], [2],             [10, 12, 7], [4, 11]]  # printing original listprint("The original list is : " + str(test_list))  # Counter gets the frequencies of counts# map and len gets lengths of sublistres = dict(Counter(map(len, test_list)))  # printing resultprint("Row length frequencies : " + str(res))

Output:

The original list is : [[6, 3, 1], [8, 9], [2], [10, 12, 7], [4, 11]]
Row length frequencies : {3: 2, 2: 2, 1: 1}

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