R help - May 2011 - Convert dataframe with two factors from wide to long format

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
...

Thanks in advance!

Gang

	[[alternative HTML version deleted]]

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]]
>
> ______________________________________________
> 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.
David Winsemius, MD
West Hartford, CT

Hi:

library(reshape2)
d1 <- melt(d, id = 'Subj')
d1 <- cbind(d1, colsplit(d1$variable, '_', c('Time',
'Cond')))
d1 <- transform(d1,
                Time = substr(Time, 2, 2),
                Cond = substr(Cond, 5, 5))[c(1, 4, 5, 3)]
str(d1)
d1

You can decide whether to leave Time and Cond as character or to
convert them to numeric or factor.

HTH,
Dennis

On Sun, May 22, 2011 at 2:25 PM, Gang Chen <gangchen6 at gmail.com>
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
> ...
>
> Thanks in advance!
>
> Gang
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> 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.
>