Hi,
I have data on stomach contents. Possible prey species are in the hundreds, so a list of prey codes has been in used in many labs doing this kind of work.
When comes time to do analyses on these data one often wants to regroup prey in broader categories, especially for rare prey.
In SAS you can nest a large number of "if-else", or do this more cleanly with "select" like this:
select;
when (149 <= prey <=150) preyGr= 150;
when (186 <= prey <= 187) preyGr= 187;
when (prey= 438) preyGr= 438;
when (prey= 430) preyGr= 430;
when (prey= 436) preyGr= 436;
when (prey= 431) preyGr= 431;
when (prey= 451) preyGr= 451;
when (prey= 461) preyGr= 461;
when (prey= 478) preyGr= 478;
when (prey= 572) preyGr= 572;
when (692 <= prey <= 695 ) preyGr= 692;
when (808 <= prey <= 826, 830 <= prey <= 832 ) preyGr= 808;
when (997 <= prey <= 998, 792 <= prey <= 796) preyGr= 792;
when (882 <= prey <= 909) preyGr= 882;
when (prey in (999, 125, 994)) preyGr= 9994;
otherwise preyGr= 1;
end; *select;
The number of transformations is usually much larger than this short example.
What is the best way of doing this in R?
Sincerely,
Denis Chabot
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