[R] is.null doesn't work

[jim holtman]

'v' appears to be a list:

>  v=c(`-`,`+`,1,`^`,`^`,NA,NA,"X",9,"X",2)
>  i2=16
>  v[i2]
[[1]]
NULL

> str(v)
List of 11
 $ :function (e1, e2)
 $ :function (e1, e2)
 $ : num 1
 $ :function (e1, e2)
 $ :function (e1, e2)
 $ : logi NA
 $ : logi NA
 $ : chr "X"
 $ : num 9
 $ : chr "X"
 $ : num 2

because you used backquotes(`) on the '-'; notice the difference:

> str(c(`-`,1))
List of 2
 $ :function (e1, e2)
 $ : num 1
> str(c('-',1))
 chr [1:2] "-" "1"
>




On 7/12/07, Atte Tenkanen <attenka at utu.fi> wrote:
> Hi,
>
> What's wrong here?:
>
> > v=c(`-`,`+`,1,`^`,`^`,NA,NA,"X",9,"X",2)
> > i2=16
> > v[i2]
> [[1]]
> NULL
>
> > is.null(v[i2])
> [1] FALSE
>
> Is it a bug or have I misunderstood something?
>
> Atte Tenkanen
> University of Turku, Finland
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?