Hi everybody,

I have data in the format of the example data below where essentially a
large number of indicator variables (coded [0,1]) reflect traits of the
same id across multiple rows. I need to represent the data in a 1 row per
id format. I see this as being similar to converting from long to wide
format, however, there is no time component here: The multiple rows here
are all characteristics observed at the same measurement occasion. So,
really I just need an individual sum for each variable (for a large number
of variables) and for these to be all saved in the same row (along with the
id variable and other demographics (e.g., "location").

Here is the example df and the method I used first:


d1<-data.frame(id=c(1,1,1,2,2,2,2,3,3,4),location=factor(c(rep(0,7),rep(1,3)),
 labels=c("A","B")),var1=as.logical(round(runif(10))),
 var2=as.logical(round(runif(10))),var3=as.logical(round(runif(10))))
d1
mysum<-function(x) aggregate(x,by=list(d1$id),sum)
d2<-sapply(d1[2:4],mysum)
d2

Any help is appreciated!!

Thanks!

Dan

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