| rapply {base} | R Documentation |
rapply is a recursive version of lapply.
rapply(object, f, classes = "ANY", deflt = NULL,
how = c("unlist", "replace", "list"), ...)
object |
A list. |
f |
A function of a single argument. |
classes |
A character vector of |
deflt |
The default result (not used if |
how |
A character string matching the three possibilities given: see ‘Details’. |
... |
additional arguments passed to the call to |
This function has two basic modes. If how = "replace", each
element of the list which is not itself a list and has a class
included in classes is replaced by the result of applying
f to the element.
If the mode is how = "list" or how = "unlist", the list
is copied, all non-list elements which have a class included in
classes are replaced by the result of applying f to the
element and all others are replaced by deflt. Finally, if
how = "unlist", unlist(recursive = TRUE) is called on
the result.
The semantics differ in detail from lapply: in
particular the arguments are evaluated before calling the C code.
If how = "unlist", a vector, otherwise a list of similar
structure to object.
Chambers, J. A. (1998)
Programming with Data.
Springer.
(rapply is only described briefly there.)
X <- list(list(a=pi, b=list(c=1:1)), d="a test")
rapply(X, function(x) x, how="replace")
rapply(X, sqrt, classes="numeric", how="replace")
rapply(X, nchar, classes="character",
deflt = as.integer(NA), how="list")
rapply(X, nchar, classes="character",
deflt = as.integer(NA), how="unlist")
rapply(X, nchar, classes="character", how="unlist")
rapply(X, log, classes="numeric", how="replace", base=2)