Re: [R] Convert dataframe with two factors from wide to long format

From: David Winsemius <dwinsemius_at_comcast.net>
Date: Sun, 22 May 2011 18:00:17 -0400

On May 22, 2011, at 5:25 PM, Gang Chen wrote:

> I know how to convert a simple dataframe from wide to long format
> with one
> varying factor. However, for a dataset with two factors like the
> following,
>
> Subj T1_Cond1 T1_Cond2 T2_Cond1 T2_Cond2
> 1 0.125869 4.108232 1.099392 5.556614
> 2 1.427940 2.170026 0.120748 1.176353
>
> How to elegantly convert to a long form as
>
> Subj Time Cond Value
> 1 1 1 0.125869
> 1 1 2 4.108232
> 1 2 1 1.099392

Assume this is a dataframe named 'tst'

require(reshape2)
ltest <- melt(tst, id.vars =1)

dcast(ltest, ubj+substr(variable, 1,2) + substr(variable, 4,8) ~. )

   ubj substr(variable, 1, 2) substr(variable, 4, 8)       NA
1   1                     T1                  Cond1 0.125869
2   1                     T1                  Cond2 4.108232
3   1                     T2                  Cond1 1.099392
4   1                     T2                  Cond2 5.556614
5   2                     T1                  Cond1 1.427940
6   2                     T1                  Cond2 2.170026
7   2                     T2                  Cond1 0.120748
8   2                     T2                  Cond2 1.176353

dcast(ltest, ubj+substr(variable, 1,2) ~ substr(variable, 4,8) )

   ubj substr(variable, 1, 2) Cond1 Cond2

1   1                     T1 0.125869 4.108232
2   1                     T2 1.099392 5.556614
3   2                     T1 1.427940 2.170026
4   2                     T2 0.120748 1.176353

The modifications to get it exactly as requested are left to the reader
> ...
>
> Thanks in advance!
>
> Gang
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

David Winsemius, MD
West Hartford, CT



R-help_at_r-project.org 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. Received on Sun 22 May 2011 - 22:08:55 GMT

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