I have a larger section of code but I've narrowed down the problem to this - So I want to return a concatenated list.
do.call(c,"X")
Error in do.call(c, "X") : second argument must be a list
So above it complains about the SECOND argument not being a list.
asimplelist=list(2,3,4)
class(asimplelist)
[1] "list"
do.call(c,asimplelist)
Error in do.call(c, asimplelist) :
'what' must be a function or character string
Why will this not return a concatenated list ? C is a legit function, and it's being passed a list?
args(do.call)
function (what, args, quote = FALSE, envir = parent.frame())
NULL
So "what" is the function argument it is complaining about.
I will answer "stealing" my answer from this comment by Nick Kennedy:
It might be better to put the c
in double quotes.
If the user has a non-function named c
in the global environment, do.call(c, dates)
will fail with the error "Error in do.call(c, list(1:3)) : 'what' must be a character string or a function"
.
Clearly it may not be best practice to define c
, but it's quite common for people to do a <- 1; b <- 2; c <- 3
.
For most purposes, R still works fine in this scenario; c(1, 2)
will still work, but do.call(c, x)
won't.
Of course if the user has redefined c
to be a function (e.g. c <- sum
), then do.call
will use the redefined function.
来源:https://stackoverflow.com/questions/42499099/do-call-doesnt-like-base-function-c-with-a-list