[R] is.null doesn't work
bates at stat.wisc.edu
Fri Jul 13 01:44:04 CEST 2007
On 7/12/07, Atte Tenkanen <attenka at utu.fi> wrote:
> Seems to work, if I unlist the argument at first ;-)
> > Hi,
> > What's wrong here?:
> > > v=c(`-`,`+`,1,`^`,`^`,NA,NA,"X",9,"X",2)
> > > i2=16
> > > v[i2]
> > []
> > NULL
> > > is.null(v[i2])
> >  FALSE
> > Is it a bug or have I misunderstood something?
v is a list with a single element which happens to be NULL.
v[], on the other hand, is NULL.
A subset of a list, obtained with "[", is a list. An element of a
list, obtained with "[[", is the native type of that element.
> > Atte Tenkanen
> > University of Turku, Finland
> R-help at stat.math.ethz.ch mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
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