R help - Sep 2010 - ifelse statement

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??

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.vialma@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??
>
> ______________________________________________
> R-help@r-project.org mailing list
> stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
-- 
Ivan CALANDRA
PhD Student
University of Hamburg
Biozentrum Grindel und Zoologisches Museum
Abt. Säugetiere
Martin-Luther-King-Platz 3
D-20146 Hamburg, GERMANY
+49(0)40 42838 6231
ivan.calandra@uni-hamburg.de

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