Inefficiency of SAS Programming
Terry Therneau wrote:
Three comments
I actually think you can write worse code in R than in SAS: more tools = more
scope for innovatively bad ideas. The ability to write bad code should not damm
a language.
I found almost all of the "improvements" to the multi-line SAS recode to be
regressions, both the SAS and the S suggestions.
a. Everyone, even those of you with no SAS backround whatsoever, immediately
understood the code. Most of the replacements are obscure. Compilers are very
good these days and computers are fast, fewer typed characters != better.
b. If I were writing the S code for such an application, it would look much
the same. I worked as a programmer in medical research for several years, and
one of the things that moved me on to graduate studies in statistics was the
realization that doing my best work meant being as UN-clever as possible in my
code.
If I were writing S code for this it would be dramatically different. I would try to be efficient and elegant but would need to remember to be a teacher at the same time. For example this kind of recode is super efficient and quick to program but would need good comments or a handbook to all of my code: c(cat=1, dog=2, giraffe=3)[animal] But I think the code is quite intuitive once you have used that construct once. There also a lot of factoring of code that could be done as others have pointed out.
Frank's comments imply that he was reading SAS macro code at the moment of peak frustration. And if you want to criticise SAS code, this is the place to look. SAS macro started out as some simple expansions, then got added on to, then added on again, and again, and .... with no overall blueprint. It is much like the farmhouse of some neighbors of mine growing up: 4 different expansions in 4 eras, and no overall guiding plan. The interior layout was "interesting" to say the least. I was once a bona fide SAS 'wizard' (and Frank was much better than me), and I can't read the stuff without grinding my teeth. S was once headed down the same road. One of the best things ever with the language was documented in the blue book "The New S Language", where Becker et al had the wisdom to scrap the macro processor.
Well put. I am amazed there hasn't been a revolt among SAS users decades ago. The S approach is also easier to debug one line at a time. Cheers, Frank
Terry Therneau
Frank E Harrell Jr Professor and Chair School of Medicine
Department of Biostatistics Vanderbilt University