How to Find Row and Column Max/Min in R

How to Find Row and Column Max/Min in R ?

Answer

In R, you can find the maximum and minimum values in each row or column of a matrix using the apply() function. This function allows you to apply a function to the rows or columns of a matrix.


✐ Examples

1 Finding Row Maximum Values of a Matrix

In this example,

  1. We have a matrix named mat.
  2. We use the apply() function to find the maximum value in each row of the matrix mat. We set the second argument of apply() to 1 to indicate that the function should be applied to rows.
  3. The max function is used as the third argument of apply() to find the maximum values.
  4. We assign the resulting row maxima to a variable named row_max.
  5. We print the row_max to the console to display the maximum values in each row.

R Program

mat <- matrix(c(1, 2, 3, 4, 5, 6), nrow = 2)
row_max <- apply(mat, 1, max)
print(row_max)

Output

[1] 3 6

2 Finding Column Maximum Values of a Matrix

In this example,

  1. We have a matrix named mat.
  2. We use the apply() function to find the maximum value in each column of the matrix mat. We set the second argument of apply() to 2 to indicate that the function should be applied to columns.
  3. The max function is used as the third argument of apply() to find the maximum values.
  4. We assign the resulting column maxima to a variable named col_max.
  5. We print the col_max to the console to display the maximum values in each column.

R Program

mat <- matrix(c(1, 2, 3, 4, 5, 6), nrow = 2)
col_max <- apply(mat, 2, max)
print(col_max)

Output

[1] 4 5 6

3 Finding Row Minimum Values of a Matrix

In this example,

  1. We have a matrix named mat.
  2. We use the apply() function to find the minimum value in each row of the matrix mat. We set the second argument of apply() to 1 to indicate that the function should be applied to rows.
  3. The min function is used as the third argument of apply() to find the minimum values.
  4. We assign the resulting row minima to a variable named row_min.
  5. We print the row_min to the console to display the minimum values in each row.

R Program

mat <- matrix(c(1, 2, 3, 4, 5, 6), nrow = 2)
row_min <- apply(mat, 1, min)
print(row_min)

Output

[1] 1 4

4 Finding Column Minimum Values of a Matrix

In this example,

  1. We have a matrix named mat.
  2. We use the apply() function to find the minimum value in each column of the matrix mat. We set the second argument of apply() to 2 to indicate that the function should be applied to columns.
  3. The min function is used as the third argument of apply() to find the minimum values.
  4. We assign the resulting column minima to a variable named col_min.
  5. We print the col_min to the console to display the minimum values in each column.

R Program

mat <- matrix(c(1, 2, 3, 4, 5, 6), nrow = 2)
col_min <- apply(mat, 2, min)
print(col_min)

Output

[1] 1 2 3

Summary

In this tutorial, we learned How to Find Row and Column Max/Min in R language with well detailed examples.


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