Dear all,

how can I, with R, transform a presence-only table (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)) into a presence-absence (0/1) matrix of species occurrences across sites, as given in the below example?

Thanks a lot for your help!
Christian



My initial table:

species lat     lon
sp1     10      10
sp1     10      30
sp1     20      10
sp1     20      20
sp1     20      30
sp2     10      30
sp2     20      30
sp2     30      30


My desired matrix:

lat     lon     sp1     sp2
10      10      1       0
10      20      0       0
10      30      1       1
20      10      1       0
20      20      1       0
20      30      1       1
30      10      0       0
30      20      0       0
30      30      0       1


--
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

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