Matrices
In R, a matrix is a collection of elements of the same data type (numeric, character, or logical) arranged into a fixed number of rows and columns. Since you are only working with rows and columns, a matrix is called two-dimensional.
You can construct a matrix in R with the matrix() function. Consider the following example:
matrix(1:9, byrow = TRUE, nrow = 3, ncol = 3)
In the matrix() function:
- The first argument is the collection of elements that R will arrange into the rows and columns of the matrix. Here, we use 1:9 which constructs the vector c(1, 2, 3, 4, 5, 6, 7, 8, 9).
- The argument byrow indicates that the matrix is filled by the rows. This means that the matrix is filled from left to right and when the first row is completed, the filling continues on the second row. If we want the matrix to be filled by the columns, we just place byrow = FALSE.
- The third argument nrow indicates that the matrix should have three rows.
- The fourth argument ncol indicates the number of columns that the matrix should have
This exercise is part of the course
Inferential Statistics
Exercise instructions
- Construct a matrix with 5 rows and 4 columns containing the numbers 1 up to 20 and assign it to the variable
m
. Specify thebyrow
argument to beTRUE
- Print m to the console
Hands-on interactive exercise
Have a go at this exercise by completing this sample code.
# Construction of a matrix with 5 rows that contain the numbers 1 up to 20 and assign it to m
# print m to the console