check whether all elements of a list are in equal in R

Question

I have a list of several vectors. I would like to check whether all vectors in the list are equal. There's identical which only works for pairwise comparison. So I wrote the following function which looks ugly to me. Still I did not find a better solution. Here's my RE:

test_true <- list(a=c(1,2,3),b=c(1,2,3),d=c(1,2,3))
test_false <- list(a=c(1,2,3),b=c(1,2,3),d=c(1,32,13))

compareList <- function(li){
  stopifnot(length(li) > 1)
  l <- length(li)
  res <- lapply(li[-1],function(X,x) identical(X,x),x=li[[1]])
  res <- all(unlist(res))
  res
}

compareList(test_true)
compareList(test_false)

Any suggestions? Are there any native checks for identical for more than just pairwise comparison?

Answer 1

I woud do:

all.identical <- function(l) all(mapply(identical, head(l, 1), tail(l, -1)))

all.identical(test_true)
# [1] TRUE
all.identical(test_false)
# [1] FALSE