Find the mean vector of a Matrix (original) (raw)

Last Updated : 5 Dec, 2022

Given a matrix of size M x N, the task is to find the Mean Vector of the given matrix.

Examples:

Input : mat[][] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}
Output : Mean Vector is [4 5 6] Mean of column 1 is (1 + 4 + 7) / 3 = 4 Mean of column 2 is (2 + 5 + 8) / 3 = 5 Mean of column 3 is (3 + 6 + 9) / 3 = 6

Input : mat[][] = {{2, 4}, {6, 8}} Output : Mean Vector is [4 6] Mean of column 1 is (2 + 6) / 2 = 4 Mean of column 2 is (4 + 8) / 2 = 6

Approach:

Let's take a matrix mat of dimension 5x3 representing lengths, breadths, heights of 5 objects.
Now, the resulting mean vector will be a row vector of the following format :

[mean(length) mean(breadth) mean(height)]

Note: If we have a matrix of dimension M x N, then the resulting row vector will be having dimension 1 x N

Now, simply calculate the mean of each column of the matrix which will give the required mean vector .

Implementation:

C++ `

// C++ program to find mean vector // of given matrix #include <bits/stdc++.h> using namespace std; #define rows 3 #define cols 3

// Function to find mean vector void meanVector(int mat[rows][cols]) { cout << "[ ";

// loop to traverse each column
for (int i = 0; i < rows; i++) {

    // to calculate mean of each row
    double mean = 0.00;

    // to store sum of elements of a column
    int sum = 0;

    for (int j = 0; j < cols; j++)
        sum += mat[j][i];

    mean = sum / rows;
    cout << mean << " ";
}

cout << "]";

}

// Drivers code int main() {

int mat[rows][cols] = { { 1, 2, 3 },
                        { 4, 5, 6 },
                        { 7, 8, 9 } };

meanVector(mat);

return 0;

}

Java

// Java program to find // mean vector of given matrix import java.io.*;

class GFG { static int rows = 3; static int cols = 3;

// Function to // find mean vector static void meanVector(int mat[][]) { System.out.print("[ ");

// loop to traverse 
// each column
for (int i = 0; i < rows; i++) 
{

    // to calculate mean
    // of each row
    double mean = 0.00;

    // to store sum of
    // elements of a column
    int sum = 0;

    for (int j = 0; j < cols; j++)
        sum += mat[j][i];

    mean = sum / rows;
    System.out.print((int)mean + " ");
}

System.out.print("]");

}

// Driver code public static void main (String[] args) { int mat[][] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

meanVector(mat);

} }

// This code is contributed // by anuj_67.

Python3

Python3 program to find

mean vector of given

matrix

rows = 3; cols = 3;

Function to

find mean vector

def meanVector(mat): print("[ ", end = "");

# loop to traverse
# each column
for i in range(rows):
    
    # to calculate
    # mean of each row
    mean = 0.00;

    # to store sum of 
    # elements of a column
    sum = 0;

    for j in range(cols):
        sum = sum + mat[j][i];

    mean = int(sum /rows);
    print(mean, end = " ");

print("]");

Driver Code

mat = [[1, 2, 3], [4, 5, 6], [7, 8, 9]];

meanVector(mat);

This code is contributed

by mits

C#

// C# program to find // mean vector of given matrix using System;

class GFG { static int rows = 3; static int cols = 3;

// Function to // find mean vector static void meanVector(int [,]mat) { Console.Write("[ ");

// loop to traverse 
// each column
for (int i = 0; i < rows; i++) 
{

    // to calculate mean
    // of each row
    double mean = 0.00;

    // to store sum of
    // elements of a column
    int sum = 0;

    for (int j = 0; j < cols; j++)
        sum += mat[j, i];

    mean = sum / rows;
    Console.Write((int)mean + " ");
}

Console.Write("]");

}

// Driver code public static void Main () { int[,] mat = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};

meanVector(mat);

} }

// This code is contributed // by anuj_67.

PHP

JavaScript

`

Time Complexity: O(m * n), where m and n are the numbers of rows and columns respectively.
Auxiliary Space: O(1)