R – Get Specific Column of Matrix
To get a specific column of a matrix, specify the column number preceded by a comma, in square brackets, after the matrix variable name. This expression returns the required row as a vector.
In this tutorial, we will learn how to get a single column from a Matrix, with examples.
Syntax
The syntax of the expression to get a column at given number/position/index in a matrix is
X[, column]
where
| Argument | Description |
|---|---|
| X | A matrix. |
| column | Column number. |
Return Value
The expression returns the column as a vector from matrix X at given column number.
Examples
In the following program, we create a matrix and get the column at position 2.
example.R
data <- c(2, 4, 7, 5, 10, 8)
A <- matrix(data, nrow = 2)
column <- A[, 2]
print("Matrix A")
print(A)
print("Column")
print(column) Output
[1] "Matrix A"
[,1] [,2] [,3]
[1,] 2 7 10
[2,] 4 5 8
[1] "Column"
[1] 7 5 If the column number is out of bounds for given matrix, then R throws Error “subscript out of bounds”.
Let us try to get a row at column = 5, where the matrix has only 3 rows.
example.R
data <- c(2, 4, 7, 5, 10, 8) A <- matrix(data, nrow = 2) column <- A[, 5]
Output
Error in A[, 5] : subscript out of bounds
Conclusion
In this R Tutorial, we learned how to get specific column of a Matrix at given column position in R, with the help of examples.