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.
matrix(data = NA, nrow = 1, ncol = 1, byrow = FALSE, dimnames = NULL) as.matrix(x, ...) ## S3 method for class 'data.frame': as.matrix((x, rownames.force = NA, ...) is.matrix(x))
- an optional data vector (including a list or
expressionvector). Non-atomic classed R objects are coerced by
as.vectorand all attributes discarded.
- the desired number of rows.
- the desired number of columns.
- logical. If
FALSE(the default) the matrix is filled by columns, otherwise the matrix is filled by rows.
dimnamesattribute for the matrix:
listof length 2 giving the row and column names respectively. An empty list is treated as
NULL, and a list of length one as row names. The list can be named, and the list names will be used as names for the dimensions.
- an R object.
- additional arguments to be passed to or from methods.
- logical indicating if the resulting matrix should have character (rather than
rownames. The default,
NULLrownames if the data frame has ‘automatic’ row.names or for a zero-row data frame.
If there are too few elements in
data to fill the matrix, then the elements in
data are recycled. If
data has length zero,
NA of an appropriate type is used for atomic vectors (
NULL for lists.
x is a vector and has a
"dim" attribute of length 2) and
FALSE otherwise. Note that a
data.frame is not a matrix by this test. The function is generic: you can write methods to handle specific classes of objects, see InternalMethods.
as.matrix is a generic function. The method for data frames will return a character matrix if there is only atomic columns and any non-(numeric/logical/complex) column, applying
as.vector to factors and
format to other non-character columns. Otherwise, the usual coercion hierarchy (logical < integer < double < complex) will be used, e.g., all-logical data frames will be coerced to a logical matrix, mixed logical-integer will give a integer matrix, etc.
When coercing a vector, it produces a one-column matrix, and promotes the names (if any) of the vector to the rownames of the matrix.
is.matrix is a primitive function.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
If you just want to convert a vector to a matrix, something like
dim(x) <- c(nx, ny) dimnames(x) <- list(row_names, col_names)
will avoid duplicating
data.matrix, which attempts to convert to a numeric matrix.
A matrix is the special case of a two-dimensional
is.matrix(as.matrix(1:10)) !is.matrix(warpbreaks) # data.frame, NOT matrix! warpbreaks[1:10,] as.matrix(warpbreaks[1:10,]) # using as.matrix.data.frame(.) method ## Example of setting row and column names mdat <- matrix(c(1,2,3, 11,12,13), nrow = 2, ncol = 3, byrow = TRUE, dimnames = list(c("row1", "row2"), c("C.1", "C.2", "C.3"))) mdat
Documentation reproduced from R 3.0.2. License: GPL-2.