search for: some_factor

Hello all I have a big data frame and I regularly want to break it down into subsets, calculate some new data, and add it back to the data frame. At the moment my technique seems a bit ugly and embarrassing. Something like: result <- by(mydata, mydata$some_factor, function (x) { # do something to create a vector v with length(v) == nrow(x) return(v) }) # now result has a big list, argh... how do I put it neatly back into the mydata data frame? for (i in unique(mydata$some_factor) { mydata$newvar[mydata$somefactor ==i] <- result[[i]] } What should I b...

...nd.b.1" when it is actually "a.and.b" "a_and_b" The docs do not reflect this very major change in behavior from 1.8.x to 1.9.0. This change causes numerous R codes to fail in senarios like the following. Suppose I have a data file, example.dat, like this: a b x some_factor 1 1 0.4 orange 2 1 0.3 blue 1 1 0.2 dog 2 1 0.1 orange 1 2 0.4 blue 2 2 0.3 dog 1 2 0.2 orange 2 2 0.1 blue To read and use this in a version independent way, I've tried to write version-aware code, but this is difficult as '_' is not syntactically valid prior to R 1.9.0. If it were,...