Gmisc (version 3.0.3)

fastDoCall: An alternative to the internal do.call

Description

The do.call can be somewhat slow, especially when working with large objects. This function is based upon the suggestions from Hadley Wickham on the R mailing list. Also thanks to Tommy at StackOverflow for suggesting how to handle double and triple colon operators, ::, further enhancing the function.

Usage

fastDoCall(what, args, quote = FALSE, envir = parent.frame())

Arguments

what

either a function or a non-empty character string naming the function to be called.

args

a list of arguments to the function call. The names attribute of args gives the argument names.

quote

a logical value indicating whether to quote the arguments.

envir

an environment within which to evaluate the call. This will be most useful if what is a character string and the arguments are symbols or quoted expressions.

Examples

fastDoCall("complex", list(imaginary = 1:3))

## if we already have a list (e.g. a data frame)
## we need c() to add further arguments
tmp <- expand.grid(letters[1:2], 1:3, c("+", "-"))
fastDoCall("paste", c(tmp, sep = ""))

## examples of where objects will be found.
A <- 2
f <- function(x) print(x^2)
env <- new.env()
assign("A", 10, envir = env)
assign("f", f, envir = env)
f <- function(x) print(x)
f(A)                                      # 2
fastDoCall("f", list(A))                     # 2
fastDoCall("f", list(A), envir = env)        # 4
fastDoCall(f, list(A), envir = env)          # 2
fastDoCall("f", list(quote(A)), envir = env) # 100
fastDoCall(f, list(quote(A)), envir = env)   # 10
fastDoCall("f", list(as.name("A")), envir = env) # 100

eval(call("f", A))                      # 2
eval(call("f", quote(A)))               # 2
eval(call("f", A), envir = env)         # 4
eval(call("f", quote(A)), envir = env)  # 100