Hello,
You have to be aware that mylist[1] and mylist[[1]] are different things.
class(mylist[1])
[1] "list"
class(mylist[[1]])
[1] "NULL"
Apparently you want/need the latter:
is.null(mylist[[1]])
[1] TRUE
Hope this helps,
Rui Barradas
Em 15-06-2017 16:33, ce escreveu:
Hi
I have a list :
mylist <- list( a = NULL, b = 1, c = 2 )
mylist[1]
$a
NULL
is.null(mylist[1])
[1] FALSE
is.null(mylist$a)
[1] TRUE
why? I need to use mylist[1]
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______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
