[R] how to reverse a list

Weiwei Shi helprhelp at gmail.com
Thu Apr 12 00:13:31 CEST 2007


thanks. split() is what I needed.

On 4/11/07, jim holtman <jholtman at gmail.com> wrote:
> try this:
>
> > x <- cbind(unlist(t0), names(t0))
> > x
>   [,1] [,2]
> a "1"  "a"
> b "1"  "b"
> c "2"  "c"
> d "1"  "d"
> > split(x[,2], x[,1])
> $`1`
>   a   b   d
> "a" "b" "d"
>
> $`2`
>   c
> "c"
>
>
>
> On 4/11/07, Weiwei Shi <helprhelp at gmail.com> wrote:
> > Hi, there:
> >
> > I am wondering if there is a quick way to "reverse" a list like this:
> >
> > t0 <- list(a=1, b=1, c=2, d=1)
> >
> > reverst t0 to t1
> >
> > > t1
> > $`1`
> > [1] "a" "b" "d"
> >
> > $`2`
> > [1] "c"
> >
> >
> > thanks.
> > --
> > Weiwei Shi, Ph.D
> > Research Scientist
> > GeneGO, Inc.
> >
> > "Did you always know?"
> > "No, I did not. But I believed..."
> > ---Matrix III
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
> >
>
>
> --
> Jim Holtman
> Cincinnati, OH
> +1 513 646 9390
>
> What is the problem you are trying to solve?
>


-- 
Weiwei Shi, Ph.D
Research Scientist
GeneGO, Inc.

"Did you always know?"
"No, I did not. But I believed..."
---Matrix III



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