Apply a Function to Multiple List or Vector Arguments

Applies a function to the specified multiple list or vector arguments. (Vectorize vectorizes a function with a list of arguments.)

Usage

Arguments

FUN	the function to apply.
...	the multiple list or vector arguments whose individual elements are passed to FUN.
MoreArgs	an optional list of additional arguments passed to FUN.
SIMPLIFY	a logical flag. If TRUE (the default), the result is simplified to a vector or a matrix, if possible.
USE.NAMES	a logical flag. If TRUE (the default), the names of the first ... argument are used as the names for the result.
vectorize.args	the arguments of FUN to be vectorized. The default is all argument names of FUN, other than any ... argument.

Details

mapply applies FUN to the first elements of the ... arguments, then to the second elements of these arguments, and so on. The elements of the ... argument values are passed as individual arguments to FUN with the argument names specified for the ... arguments, followed by any arguments in MoreArgs.

If the lengths of the ... argument values are different, the shorter values are repeated cyclically. Warnings are generated if the longest length is not a multiple of the shorter lengths.

Vectorize generates a function with the same arguments as FUN that passes FUN to the mapply function. The arguments specified by vectorize.args are passed as the ... arguments of mapply, so they are "vectorized". Any arguments to FUN that are not specified by vectorize.args, including any ... argument, are passed in the MoreArgs argument to mapply.

The function returned by Vectorize checks whether its arguments are missing. Only arguments explicitly passed to this function are evaluated and passed to mapply. Thus, if an argument with a default is specified by vectorize.args, it is "vectorized" only if it is explicitly passed to the function. If the argument is missing and its default value is used, the default value is not vectorized.

mapply	returns a list, a vector, or a matrix.
Vectorize	returns a function. See Details for more information.

mapply(paste, 1:3, 4:6) # [1] "1 4" "2 5" "3 6"

mapply(paste, 1:3, 4:8) # Warning message: # longer argument not a multiple of length of shorter # [1] "1 4" "2 5" "3 6" "1 7" "2 8"

mapply(paste, 1:3, 4:6, sep=LETTERS[1:3]) # [1] "1A4" "2B5" "3C6"

mapply(paste, 1:6, 7:9, MoreArgs=list(sep='-')) # [1] "1-7" "2-8" "3-9" "4-7" "5-8" "6-9"

mapply(paste, 1:2, 3:4, MoreArgs=list(sep='-'), SIMPLIFY=FALSE) # [[1]] # [1] "1-3" # # [[2]] # [1] "2-4"

# simplify to a matrix if FUN returns a vector, and SIMPLIFY=TRUE mapply(paste, 1:2, MoreArgs=list(3:4)) # [,1] [,2] # [1,] "1 3" "2 3" # [2,] "1 4" "2 4"

mapply(paste, 1:2, MoreArgs=list(3:4), SIMPLIFY=FALSE) # [[1]] # [1] "1 3" "1 4" # # [[2]] # [1] "2 3" "2 4"

# use names from first vectorized argument, if USE.NAMES=TRUE mapply(paste, c(aa=1,bb=2,cc=3), c(dd=4,ee=5,ff=6)) # aa bb cc # "1 4" "2 5" "3 6" mapply(paste, c(aa=1,bb=2,cc=3), c(dd=4,ee=5,ff=6), USE.NAMES=FALSE) # [1] "1 4" "2 5" "3 6"

# apply FUN to corresponding elements of a list and a vector mapply(matrix, list(aa = 1:12, bb=1:4, cc=1:6), nrow=c(3,2,2)) # $aa # [,1] [,2] [,3] [,4] # [1,] 1 4 7 10 # [2,] 2 5 8 11 # [3,] 3 6 9 12 # # $bb # [,1] [,2] # [1,] 1 3 # [2,] 2 4 # # $cc # [,1] [,2] [,3] # [1,] 1 3 5 # [2,] 2 4 6

rr <- function(x=42, times=1) rep.int(x,times=times) vrr <- Vectorize(rr) vrr(times=1:4) # [[1]] # [1] 42 # # [[2]] # [1] 42 42 # # [[3]] # [1] 42 42 42 # # [[4]] # [1] 42 42 42 42

f <- function(x=1:3, y=4:6) c(x,y) vf <- Vectorize(f, SIMPLIFY = FALSE) f(1:3,4:6) # [1] 1 2 3 4 5 6 vf(1:3,4:6) # [[1]] # [1] 1 4 # # [[2]] # [1] 2 5 # # [[3]] # [1] 3 6

vf(1:3) # Only vectorizes x (given), not y (default) # [[1]] # [1] 1 4 5 6 # # [[2]] # [1] 2 4 5 6 # # [[3]] # [1] 3 4 5 6

# vf2 only vectorizes argument x, even if y is given vf2 <- Vectorize(f, "x", SIMPLIFY = FALSE) vf2(1:3,11:13) # [[1]] # [1] 1 11 12 13 # # [[2]] # [1] 2 11 12 13 # # [[3]] # [1] 3 11 12 13

Description

Usage

Arguments

Details