Hi,
Not sure since I've never done it, but shouldn't it be NA instead of NULL?
Ivan
Le 9/17/2010 15:23, n.via...@libero.it a écrit :
> Dear list,
> I have a question I'm trying to use the following command in R, but it gives
> me an error message.The command is:
>
> data<-ddply(data,c("year","name"), transform, check1=ifelse(check1==1&
> check2==1, 1,NULL))
>
> so in my data frame I already have the check1 variable, if the conditions
> (check1==1& check2==1) is respected, check has to have 1 as value, whereas if
> it is not I want that variable to maintain its value.
> Anyone knows, how to do this, by doing this for name and year??
>
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--
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. Säugetiere
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D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calan...@uni-hamburg.de
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