Dear all, Apologies for this beginner's question. I have a variable Price, which is associated with factors Season and Crop, each of which have several levels. The Price variable contains missing values (NA), which I want to substitute by the mean of the remaining (non-NA) Price values of the same Season-Crop combination of levels.
Price Crop Season 10 Rice Summer 12 Rice Summer NA Rice Summer 8 Rice Winter 9 Wheat Summer Price[is.na(Price)] gives me the missing values, and by(Price, list(Crop, Season), mean, na.rm = T) the values I want to impute. What I've not been able to figure out, by looking at by and the various incarnations of apply, is how to do the actual substitution. Any help would be much appreciated. Jan Smit ______________________________________________ [EMAIL PROTECTED] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
