I have list with two functions:
foo <- function() { print('foo') }
bar <- function() {}
l <- list(foo, bar)
How can I remove function foo without knowing its index?
I've tried this (to get indexes for sub setting):
> which(l == foo)
Error in l == foo :
comparison (1) is possible only for atomic and list types
Is there easy way to remove non-atomic from list without looping?
Assuming the code in the question, use identical we can get its index like this:
Position(function(fun) identical(fun, foo), l)
## [1] 1
or
which(sapply(l, identical, foo))
## [1] 1
If you know something about the functions you may be able to run them and select based on the output. For the example this works:
Position(function(f) length(f()), l)
## [1] 1
If you have control over the creation of the list an easy approach is to create the list with names:
l2 <- list(foo = foo, bar = bar)
nms <- setdiff(names(l2), "foo")
If we know that foo is in l once then
l[-ix]
or in the case of l2:
l2[nms]
or use the alternative given by @Gregor:
Filter(function(x) !identical(x, foo), l)
If foo might not be in l you will need to check that condition first. Position and match return NA if there is no match (or specify the nomatch argument to either) and which returns intetger(0) for a no match.
If foo can be in l more than once then use the which alternative above.
Note that which and Filter check every position but match and Position stop after the first match.
