| matrix {base} | R Documentation |
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)
data |
an optional data vector (including a list or
|
nrow |
the desired number of rows. |
ncol |
the desired number of columns. |
byrow |
logical. If |
dimnames |
A |
x |
an R object. |
... |
additional arguments to be passed to or from methods. |
rownames.force |
logical indicating if the resulting matrix
should have character (rather than |
If one of nrow or ncol is not given, an attempt is
made to infer it from the length of data and the other
parameter. If neither is given, a one-column matrix is returned.
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 (0 for raw vectors) and NULL for lists.
is.matrix returns TRUE if 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 any
non-(numeric/logical/complex) column, applying format to
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.
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
x.
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
data.matrix, which attempts to convert to a numeric
matrix.
A matrix is the special case of a two-dimensional array.
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