2009/2/27 Peter Dalgaard <p.dalga...@biostat.ku.dk>: > Presumably, something like > > IF &N. = 1 THEN SUB_N = 1; > ELSE IF &N. < 5 THEN SUB_N = &N.-1; > ELSE IF &N. < 16 THEN SUB_N = &N.-2; > ELSE SUB_N = &N.-3; > > would work, provided that 2, 5, 16 are impossible values. Problem is that it > actually makes the code harder to grasp, so experienced SAS programmers go > for the dumb but readable code like the above.
I'm not sure which is easier to grasp. When I first saw the original version I thought it was an odd way of doing "SUB_N = &N.". Only then did I have a closer look and spot the missing 2, 5, and 16. A comment would have been very enlightening. But there was nothing relevant. > In R, the cleanest I can think of is > > subn <- match(n, setdiff(1:19, c(2,5,16))) > > or maybe just > > subn <- match(n, c(1, 3:4, 6:15, 17:19)) > > although > > subn <- factor(n, levels = c(1, 3:4, 6:15, 17:19)) > > might be what is really wanted I think the important thing with any programming is to make sure what you want is expressed in words somewhere. If not in the code, then in the comments. And operations like this should be abstracted into functions. All the examples of SAS code I've seen seem to fall into the old practices of writing great long 'scripts', with minimal code-reuse and encapsulation of useful functionality. If these SAS scripts are then given to new SAS programmers then the chances are they will follow these bad practices. Show them well-written R code (or C, or Python) and maybe they can implement those good practices into their SAS work. Assuming SAS can do that. I'm not sure. Barry ______________________________________________ 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.
