matrix(data = NA, nrow = 1, ncol = 1, byrow = FALSE, dimnames = NULL) as.matrix(x) is.matrix(x)
matrix creates a matrix from the given set of values.
nrow gives the desired number of rows and ncol the
desired number of columns. 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. If byrow is FALSE
(the default) the matrix is filled by columns, otherwise the matrix is
filled by rows. A dimnames attribute for the matrix can be
specified with the optional dimnames argument (which thus has
to be a list of length 2).
as.matrix attempts to turn its argument into a matrix. This
function is generic with a default and a data.frame method.
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.
data.matrix.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