R: Matrices

matrix {base}

R Documentation

Matrices

Description

matrix creates a matrix from the given set of values.

as.matrix attempts to turn its argument into a matrix.

is.matrix tests if its argument is a (strict) matrix.

Usage

matrix(data = NA, nrow = 1, ncol = 1, byrow = FALSE, dimnames = NULL)
as.matrix(x)
is.matrix(x)

Arguments

data

an optional data vector.

nrow

the desired number of rows

ncol

the desired number of columns

byrow

logical. If FALSE (the default) the matrix is filled by columns, otherwise the matrix is filled by rows.

dimnames

A dimnames attribute for the matrix: a list of length 2.

x

an R object.

Details

If either of nrow or ncol is not given, an attempt is made to infer it from the length of data and the other parameter.

is.matrix returns TRUE if x is a matrix (i.e., it not a data.frame and has a dim attribute of length 2) and FALSE otherwise.

Examples

is.matrix(as.matrix(1:10))
data(warpbreaks)
!is.matrix(warpbreaks)# data.frame, NOT matrix!
str(warpbreaks)
str(as.matrix(warpbreaks))#using as.matrix.data.frame(.) method