[R] using the function unique(), but asking it to ignore a column of a data.frame

[Andrew Yee]

Thanks.  But in this specific case, I would like the output to include
all three columns, including the "ignored" column (in this case, I'd
like it to ignore column a).

Thanks,
Andrew

On 7/9/07, hadley wickham <h.wickham at gmail.com> wrote:
> On 7/9/07, Andrew Yee <yee at post.harvard.edu> wrote:
> > Take for example the following data.frame:
> >
> > a<-c(1,1,5)
> > b<-c(3,2,3)
> > c<-c(5,1,5)
> > sample.data.frame<-data.frame(a=a,b=b,c=c)
> >
> > I'd like to be able to use unique(sample.data.frame), but have
> > unique() ignore column a when determining the unique elements.
> >
> > However, I figured that this would be setting for incomparables=, but
> > it appears that this funcationality hasn't been incorporated.  Is
> > there a work around for this, i.e. to be able to get unique to only
> > look at selected columns of a data frame?
>
> unique(df[,c("a","c")]) ?
>
> Hadley
>