Christian,
You need to use reshape to convert to the 'long' format.
Check the help page ?reshape for details.
>dat <- read.table('clipboard', header=TRUE)
>dat
site lat lon spec1 spec2 spec3 spec4
1 site1 10 11 1 0 1 0
2 site2 20 21 1 1 1 0
3 site3 30 31 0 1 1 1
> dat.long <- reshape(dat, varying = list(names(dat)[4:7]),
timevar="species",
times=names(dat)[4:7], direction="long")
> dat.long
site lat lon species spec1 id
1.spec1 site1 10 11 spec1 1 1
2.spec1 site2 20 21 spec1 1 2
3.spec1 site3 30 31 spec1 0 3
1.spec2 site1 10 11 spec2 0 1
2.spec2 site2 20 21 spec2 1 2
3.spec2 site3 30 31 spec2 1 3
1.spec3 site1 10 11 spec3 1 1
2.spec3 site2 20 21 spec3 1 2
3.spec3 site3 30 31 spec3 1 3
1.spec4 site1 10 11 spec4 0 1
2.spec4 site2 20 21 spec4 0 2
3.spec4 site3 30 31 spec4 1 3
> dat.long[dat.long$spec1 == 1, ]
site lat lon species spec1 id
1.spec1 site1 10 11 spec1 1 1
2.spec1 site2 20 21 spec1 1 2
2.spec2 site2 20 21 spec2 1 2
3.spec2 site3 30 31 spec2 1 3
1.spec3 site1 10 11 spec3 1 1
2.spec3 site2 20 21 spec3 1 2
3.spec3 site3 30 31 spec3 1 3
3.spec4 site3 30 31 spec4 1 3
-Christos
> -----Original Message-----
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED] On Behalf Of Christian Hof
> Sent: Friday, May 02, 2008 5:28 PM
> To: r-help@r-project.org
> Subject: [R] data transformation
>
> Dear all,
> how can I, with R, transform a presence-absence (0/1) matrix
> of species occurrences into a presence-only table (3 columns)
> with the names of the species (1st column), the lat
> information of the sites (2nd column) and the lon information
> of the sites (3rd column), as given in the below example?
> Thanks a lot for your help!
> Christian
>
>
> my dataframe:
>
> site lat lon spec1 spec2 spec3 spec4
> site1 10 11 1 0 1 0
> site2 20 21 1 1 1 0
> site3 30 31 0 1 1 1
>
>
> my desired new dataframe:
>
> species lat lon
> spec1 10 11
> spec1 20 21
> spec2 20 21
> spec2 30 31
> spec3 10 11
> spec3 20 21
> spec3 30 31
> spec4 30 31
>
>
>
> --
> Christian Hof, PhD student
>
> Center for Macroecology & Evolution
> University of Copenhagen
> www.macroecology.ku.dk
> &
> Biodiversity & Global Change Lab
> Museo Nacional de Ciencias Naturales, Madrid www.biochange-lab.eu
>
> mobile ES .. +34 697 508 519
> mobile DE .. +49 176 205 189 27
> mail .. [EMAIL PROTECTED]
> mail2 .. [EMAIL PROTECTED]
> blog .. www.vogelwart.de
>
> ______________________________________________
> R-help@r-project.org mailing list
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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.
>
>
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