Inefficiency of SAS Programming

2009/2/26 Frank E Harrell Jr <f.harrell at vanderbilt.edu>:
If anyone wants to see a prime example of how inefficient it is to program
in SAS, take a look at the SAS programs provided by the US Agency for
Healthcare Research and Quality for risk adjusting and reporting for
hospital outcomes at http://www.qualityindicators.ahrq.gov/software.htm .
?The PSSASP3.SAS program is a prime example. ?Look at how you do a vector
product in the SAS macro language to evaluate predictions from a logistic
regression model. ?I estimate that using R would easily cut the programming
time of this set of programs by a factor of 4.
 Plenty of examples ripe for sending to www.thedailywtf.com there. Like this:

    IF &N. =  1 THEN SUB_N = 1;
    IF &N. =  3 THEN SUB_N = 2;
    IF &N. =  4 THEN SUB_N = 3;
    IF &N. =  6 THEN SUB_N = 4;
    IF &N. =  7 THEN SUB_N = 5;
    IF &N. =  8 THEN SUB_N = 6;
    IF &N. =  9 THEN SUB_N = 7;
    IF &N. = 10 THEN SUB_N = 8;
    IF &N. = 11 THEN SUB_N = 9;
    IF &N. = 12 THEN SUB_N = 10;
    IF &N. = 13 THEN SUB_N = 11;
    IF &N. = 14 THEN SUB_N = 12;
    IF &N. = 15 THEN SUB_N = 13;
    IF &N. = 17 THEN SUB_N = 14;
    IF &N. = 18 THEN SUB_N = 15;
    IF &N. = 19 THEN SUB_N = 16;

Of course it's possible to write code like that in any language, it
just looks worse when it's in ALL CAPS and written in a style that
looks like the 1980s and onward never happened. The question is
whether it's possible to write this better in SAS. Most of us on this
list could write it in R in a better way.
Oh, it's definitely possible to write better SAS code than that.  This should do the trick:

   Sub_n = input(scan("1 . 2 3 . 4 5 6 7  8  9 10 11 12 13  . 14 15 16", &N, " "), 2.);

among various other ways.

But it remains true that certain operations in SAS will be quite inefficient.

---JRG
 Barry

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Inefficiency of SAS Programming

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