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# The problem: # In data.frame d for each "id" find a sum of "var1", "var2" # and keep the results in the same data.frame . d = data.frame(ss=c(1111,1111,1111,2222,2222,4444,4444,4444), id=c(1,1,1,2,2,4,4,4), var1 = round(rnorm(8),1 ), var2 = c(round(rnorm(8),1))) d varList = c("var1", "var2") # alternative way of defining a list of variables: # varList = setdiff(names(d), c("ss", "id")) for (n in varList){ t = tapply(dn, d$id, sum, na.rm=TRUE) dpaste("sum",n,sep="") = t[as.character(d$id)] }
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Topic revision: r1 - 08 Nov 2006, TheresaScott
 

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