[R] data transformation

[Christos Hatzis]

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: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Christian Hof
> Sent: Friday, May 02, 2008 5:28 PM
> To: r-help at 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 .. chof at bio.ku.dk
>      mail2 .. vogelwart at gmx.de
>       blog .. www.vogelwart.de
> 
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