Find the mean vector of a Matrix
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 5×3 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
<?php // PHP program to find mean // vector of given matrix $rows = 3; $cols = 3; // Function to find mean vector function meanVector( $mat ) { global $rows , $cols ; echo "[ " ; // loop to traverse // each column for ( $i = 0; $i < $rows ; $i ++) { // to calculate // mean of each row $mean = 0.00; // to store sum of // elements of a column $sum = 0; for ( $j = 0; $j < $cols ; $j ++) $sum += $mat [ $j ][ $i ]; $mean = $sum / $rows ; echo $mean , " " ; } echo "]" ; } // Driver Code $mat = array ( array (1, 2, 3), array (4, 5, 6), array (7, 8, 9)); meanVector( $mat ); // This code is contributed // by anuj_6 ?> |
Javascript
<script> // Javascript program to find // mean vector of given matrix var rows = 3; var cols = 3; // Function to find mean vector function meanVector(mat) { document.write( "[ " ); // Loop to traverse // each column for ( var i = 0; i < rows; i++) { // To calculate mean // of each row var mean = 0.00; // to store sum of // elements of a column var sum = 0; for ( var j = 0; j < cols; j++) sum += mat[j][i]; mean = sum / rows; document.write(mean + " " ); } document.write( "]" ); } // Driver code var mat = [ [ 1, 2, 3 ], [ 4, 5, 6 ], [ 7, 8, 9 ] ]; meanVector(mat); // This code is contributed by Kirti </script> |
Output
[ 4 5 6 ]
Time Complexity: O(m * n), where m and n are the numbers of rows and columns respectively.
Auxiliary Space: O(1)
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