Strictly recycle function parameters

recycle is called within a function and ensures the parameters in the calling function are all the same length by repeating them using rep. This function alters the environment from which it is called. It is stricter than R recycling in that it will not repeat vectors other than length one to match the longer ones, and it throws more informative errors.

Usage

recycle(..., .min = 1, .env = rlang::caller_env())

Arguments

...

the variables to recycle

.min

the minimum length of the results (defaults to 1)

.env

the environment to recycle within.

Value

the length of the longest variable

Details

NULL values are not recycled, missing values are ignored.

Examples

testfn = function(a, b, c) {
  n = recycle(a,b,c)
  print(a)
  print(b)
  print(c)
  print(n)
}

testfn(a=c(1,2,3), b="needs recycling", c=NULL)
#> [1] 1 2 3
#> [1] "needs recycling" "needs recycling" "needs recycling"
#> NULL
#> [1] 3
try(testfn(a=c(1,2,3), c=NULL))
#> [1] 1 2 3
#> Error in testfn(a = c(1, 2, 3), c = NULL) : 
#>   argument "b" is missing, with no default

testfn(a=character(), b=integer(), c=NULL)
#> character(0)
#> integer(0)
#> NULL
#> [1] 0

# inconsistent to have a zero length and a non zero length
try(testfn(a=c("a","b"), b=integer(), c=NULL))
#> Error : Parameter `b` is/are the wrong lengths. They should be length 2 (or 1)