| apply {applys} | R Documentation |
Returns a vector or array or list of values obtained by applying
a function to margins of an array or matrix.
apply(x, margin, FUN);If X is not an array but an object of a class with a non-null dim value
(such as a data frame), apply attempts to coerce it to an array via
as.matrix if it is two-dimensional (e.g., a data frame) or via
as.array.
FUN Is found by a call to match.fun And typically Is either a function Or a symbol (e.g., a backquoted name) Or a character string specifying a function to be searched for from the environment of the call to apply.
Arguments in ... cannot have the same name as any of the other
arguments, And care may be needed to avoid partial matching to MARGIN Or
FUN. In general-purpose code it Is good practice to name the first three
arguments if ... Is passed through: this both avoids Partial matching To
MARGIN Or FUN And ensures that a sensible Error message Is given If
arguments named X, MARGIN Or FUN are passed through ....
If each call to FUN returns a vector of length n, then apply
returns an array of dimension c(n, dim(X)[MARGIN]) if n > 1.
If n equals 1, apply returns a vector if MARGIN has length 1 and an array
of dimension dim(X)[MARGIN] otherwise. If n is 0, the result has length
0 but not necessarily the ‘correct’ dimension.
If the calls To FUN Return vectors Of different lengths, apply returns a list Of length prod(Dim(X)[MARGIN]) With Dim Set To MARGIN If this has length greater than one.
In all cases the result Is coerced by as.vector to one of the basic vector types before the dimensions are set, so that (for example) factor results will be coerced to a character array.