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