Python – Get Matrix Mean

Given a Matrix, Find its mean.

Input : test_list = [[5, 6, 7], [7, 5, 6]] Output : 6.0 Explanation : 36 / 6 = 6.0 
Input : test_list = [[5, 6, 7, 4, 8]] Output : 6.0 Explanation : 30 / 5 = 6.0

Method #1 : Using list comprehension + sum() + len() + zip()

The combination of above functions can be used to solve this problem. In this, we perform the mean calculation using sum() and len(), zip() along with * operator does task of extracting each element of rows of matrix.

Python3

# Python3 code to demonstrate working of
# Matrix Mean
# Using list comprehension + sum() + len() + zip()

# initializing lists
test_list = [[5, 6, 3], [8, 3, 1], [9, 10, 4], [8, 4, 2]]

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

# zip() to get all elements
# sum() / len() gives mean
# extracts column mean
res = [sum(idx) / len(idx) for idx in zip(*test_list)]

# extracts all elements mean
res = sum(res) / len(res)

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

Output

The original list : [[5, 6, 3], [8, 3, 1], [9, 10, 4], [8, 4, 2]]
Matrix Mean : 5.25

Method #2 : Using mean() + zip() + list comprehension

This is another method in which this task can be performed. In this, we extract mean using inbuilt method of mean() .

Python3

# Python3 code to demonstrate working of
# Matrix Mean
# Using mean() + zip() + list comprehension
from statistics import mean

# initializing lists
test_list = [[5, 6, 3], [8, 3, 1], [9, 10, 4], [8, 4, 2]]

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

# zip() to get all elements
# mean() gives mean
# extracts column mean
res = [mean(idx) for idx in zip(*test_list)]

# extracts all elements mean
res = mean(res)

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

Output

The original list : [[5, 6, 3], [8, 3, 1], [9, 10, 4], [8, 4, 2]]
Matrix Mean : 5.25

Method #3 : Using extend() and mean() method of statistics module

Python3

# Python3 code to demonstrate working of
# Matrix Mean
import statistics
# initializing lists
test_list = [[5, 6, 3], [8, 3, 1], [9, 10, 4], [8, 4, 2]]

# printing original list
print("The original list : " + str(test_list))
x=[]
for i in test_list:
    x.extend(i)
res=statistics.mean(x)
# printing result
print("Matrix Mean : " + str(res))

Output

The original list : [[5, 6, 3], [8, 3, 1], [9, 10, 4], [8, 4, 2]]
Matrix Mean : 5.25