Hello,

I'm working with a very large dataset (250,000+ lines in its' current form)
that includes presence only data on various species (which is nested within
different sites and sampling dates). I need to convert this into a dataset
with presence/absence for each species. For example, I would like to expand
"My current data" to "Desired data":

My current data

Species Site Date
a 1 1
b 1 1
b 1 2
c 1 3

Desired data

Species Present Site Date
a 1 1 1
b 1 1 1
c 0 1 1
a 0 2 2
b 1 2 2
C 0 2 2
a 0 3 3
b 0 3 3
c 1 3 3

I've scoured the web, including Rseek and haven't found a resolution (and
note that a similar question was asked sometime in 2011 without an answer).
Does anyone have any thoughts? Thank you in advance.

--

Matthew D. Venesky, Ph.D.

Postdoctoral Research Associate,
Department of Integrative Biology,
The University of South Florida,
Tampa, FL 33620

Website: http://mvenesky.myweb.usf.edu/

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