Apply function to each column of matrix in R

In this article, we will explore a method to apply the function to each matrix column by using R Programming Language.

How to apply the function to each column of the matrix

The function ‘apply()’ is used to apply the function to each column of the matrix. By using these methods provided by R, it is easy to apply the function. The method to apply the function to each column of the matrix is

This method is used to apply the function to each column of the matrix. The syntax is as follows

apply(X, MARGIN, FUN)

Where:

• X: Name of the matrix or data frame.
• MARGIN: Dimension to operate across. Use 1 for row, 2 for column.
• FUN: The function to apply.

In the below example, we calculated mean of each column by using the function apply().

R

a=c(12,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47)

#creating matrix
mat = matrix(a, nrow=3)
print("original matrix")
print(mat)

print("Applying function to each column for calculating mean")
result = apply(mat, 2, mean)
print(result)

Output:

[1] "original matrix"
      [,1] [,2] [,3] [,4] [,5] [,6]
[1,]   12   19   25   31   37   43
[2,]   15   21   27   33   39   45
[3,]   17   23   29   35   41   47

[1] "Applying function to each column for calculating mean"
[1] 14.66667  21.00000  27.00000  33.00000  39.00000  45.00000

In the below example, we calculated sum of each column by using the function apply().

R

#creating matrix
mat = matrix(55:74, nrow=5)
print("original matrix")
print(mat)

print("Applying function to each column for calculating sum")
result <- apply(mat, 2, sum)
print(result)

Output:

[1] "original matrix"
       [,1] [,2] [,3] [,4]
[1,]   55   60   65   70
[2,]   56   61   66   71
[3,]   57   62   67   72
[4,]   58   63   68   73
[5,]   59   64   69   74

[1] "Applying function to each column for calculating sum"
[1] 285  310  335  360

In the below example, we calculated standard deviation of each column by using the function apply().

R

#creating matrix
matrix = matrix(1:25, nrow=5)
print("original matrix")
print(matrix)

print("Applying function to each column for calculating standard deviation")
result <- apply(matrix, 2, sd)
print(result)

Output:

[1] "original matrix"
       [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16   21
[2,]    2    7   12   17   22
[3,]    3    8   13   18   23
[4,]    4    9   14   19   24
[5,]    5   10   15   20   25

[1] "Applying function to each column for calculating standard deviation"
[1] 1.581139 1.581139 1.581139 1.581139 1.581139

In the below example, we multiplied each column of elements with an integer 5 by using the function apply().

R

#creating matrix
matrix = matrix(1:25, nrow=5)
print("original matrix")
print(matrix)

print("Applying function to each column for multiplying")
result <- apply(matrix, 2, function(x) x * 5)
print(result)

Output:

[1] "original matrix"
       [,1] [,2] [,3] [,4] [,5]
[1,]    1    6   11   16   21
[2,]    2    7   12   17   22
[3,]    3    8   13   18   23
[4,]    4    9   14   19   24
[5,]    5   10   15   20   25

[1] "Applying function to each column for multiplying"
        [,1] [,2] [,3] [,4] [,5]
[1,]    5   30   55   80  105
[2,]   10   35   60   85  110
[3,]   15   40   65   90  115
[4,]   20   45   70   95  120
[5,]   25   50   75  100  125

Conclusion

In Conclusion, we learned about how to apply function to each column of matrix by using the function apply(). R language provides versatile tools and functions while dealing with matrices.