Find the mean vector of a Matrix

• Difficulty Level : Basic
• Last Updated : 13 Apr, 2021

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:
Lets take a matrix mat of dimension 5×3 representing lengths, breadths, heights of 5 objects.
Now, the resulting mean vector will be a row vector of the following format :

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 .

C++

 // C++ program to find mean vector// of given matrix#include using namespace std;#define rows 3#define cols 3 // Function to find mean vectorvoid 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 codeint 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 matriximport java.io.*; class GFG{static int rows = 3;static int cols = 3; // Function to// find mean vectorstatic 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 codepublic 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# matrixrows = 3;cols = 3; # Function to# find mean vectordef 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 Codemat = [[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 matrixusing System; class GFG{static int rows = 3;static int cols = 3; // Function to// find mean vectorstatic 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 codepublic static void Main (){    int[,] mat = {{1, 2, 3},                  {4, 5, 6},                  {7, 8, 9}};     meanVector(mat);}} // This code is contributed// by anuj_67.



Javascript


Output:
[ 4 5 6 ]

Time Complexity: O(rows * cols)

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