Hi David,
You have your answer in the question:
aggregate()
aggregate(cbind(var1,var2)~group, data=testdata, FUN=sum)
Although I am not sure what you intended to do with "testdata$x<-" as
the result cannot have the same number of rows than testdata
HTH,
Ivan
--
Ivan Calandra, ATER
University of Reims Champagne-Ardenne
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Le 26/02/15 13:02, David Studer a écrit :
Hello everybody!
I have a (probabely very easy) problem. Even though I was looking in
several r-books
I could not find a suitable function to this problem, that's why I hope
that someone here
could help me:
# Sample data:
group<-c("A","A","A","B","B","C","C","C")
var1<-c(1,0,0,1,1,0,NA,1)
var2<-c(0,1,NA,0,1,1,0,0)
testdata<-data.frame(group, var1, var2)
Now, I'd like to generate two aggregated variables:
testdata$x<- ??? should count the sum of var1 within each group (=4)
testdata$y<- ??? should count the sum of var2 within each group (=3)
Therefore I am looking for a function like ave() which does not calculate
the mean value but a sum.
Thank you for any hints!
David
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