求矩阵的均值向量
给定一个 M×N 大小的矩阵，任务是找到给定矩阵的均值向量。 例:
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
方法: 我们取一个矩阵垫的尺寸 5×3 代表 5 个物体的长度、宽度和高度。 现在，得到的均值向量将是以下格式的行向量【T11:
[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 .
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 语言(一种计算机语言，尤用于创建网站)
// 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.
Python 3
# 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.
服务器端编程语言（Professional Hypertext Preprocessor 的缩写）
<?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
?>
java 描述语言
<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 ]
时间复杂度: O(行*列)
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