[R] missing values

Ulrich Leopold uleopold at science.uva.nl
Thu Jun 27 12:18:40 CEST 2002

>>gsum <- function(v1, v2){
> +   cond <- is.na(v1)
> +   res1 <- tapply(v1[!cond], v2[!cond], function(x) sum(x[!is.na(x)]))
> +   res2 <- tapply(v1, v2, function(x) sum(is.na(x)))
> +   dat <- as.data.frame(rbind(table(v2), res1, res2))
> +   dimnames(dat)[[1]] <- c("Freq", "Sum", "Missing")
> +   cat("Missing in", deparse(substitute(v1)), ":", sum(cond), "\n")
> +   dat
> +   }

This works in the same way as before... NAs will be zeros.

I think it is rather a problem of sum. If I have only NAs sum returns 0. So 
maybe sum starts as initial value at 0 and then adds the following values.

Could this be the reason? If yes. Can I tell sum:
do not sum if there is a missing value? na.rm, is.na, na.omit do not work

Regards, Ulrich


Ulrich Leopold MSc.

Department of Physical Geography
Institute for Biodiversity and Ecosystem Dynamics
Faculty of Science
University of Amsterdam
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