On 13-12-21 5:57 PM, Göran Broström wrote:
I was recently reminded on this list that"Using 1:ncol() is bad practice (seq_len is designed for that purpose)" (Ripley) This triggers the following question: What is "good practice" for 2:ncol(x)? (This is not a joke; in a recursive situation it often makes sense to perform the calculation for the start value i = 1, then continue with a loop over the rest, "the Fortran way";) I usually use if (ncol(x) > 1) for (i in 2:ncol(x)){ .... but I can think of for (i in seq_len(x - 1)){ I <- i + 1 .... and i <- 1 while (i < ncol(x)){ i <- i + 1 .... What is "good practice" (efficient and safe)?
for (i in seq_len(x - 1) + 1) should be efficient and safe. A little less efficient, but clearer would be for (i in seq_len(x)[-1]) Duncan Murdoch ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
