R help - Nov 2010 - expand comma separated field vertically in data.frame

Hello,

I have a data.frame like this:
a	1,2,3,4	b1
b	6,7	b3

And I would like to transform it to this:
a	1	b1
a	2	b1
a	3	b1
a	4	b1
b	6	b3
b	7	b3

I have been looking at ddply but can't seem to work it out.  ANy help
would be gratefully received.

Dan

-- 
**************************************************************
Daniel Brewer, Ph.D.

Institute of Cancer Research
Molecular Carcinogenesis
Email: daniel.brewer at icr.ac.uk
**************************************************************

The Institute of Cancer Research: Royal Cancer Hospital, a charitable Company
Limited by Guarantee, Registered in England under Company No. 534147 with its
Registered Office at 123 Old Brompton Road, London SW7 3RP.

This e-mail message is confidential and for use by the a...{{dropped:2}}

Try this:

transform(x[rep(seq(nrow(x)), sapply(v.s <- strsplit(as.character(x$V2),
","), length)),], V2 = unlist(v.s))


On Fri, Nov 19, 2010 at 10:04 AM, Daniel Brewer
<daniel.brewer@icr.ac.uk>wrote:
> Hello,
>
> I have a data.frame like this:
> a       1,2,3,4 b1
> b       6,7     b3
>
> And I would like to transform it to this:
> a       1       b1
> a       2       b1
> a       3       b1
> a       4       b1
> b       6       b3
> b       7       b3
>
> I have been looking at ddply but can't seem to work it out.  ANy help
> would be gratefully received.
>
> Dan
>
> --
> **************************************************************
> Daniel Brewer, Ph.D.
>
> Institute of Cancer Research
> Molecular Carcinogenesis
> Email: daniel.brewer@icr.ac.uk
> **************************************************************
>
> The Institute of Cancer Research: Royal Cancer Hospital, a charitable
> Company Limited by Guarantee, Registered in England under Company No.
534147
> with its Registered Office at 123 Old Brompton Road, London SW7 3RP.
>
> This e-mail message is confidential and for use by the...{{dropped:20}}