[R] Inefficiency of SAS Programming

Fri Feb 27 20:05:40 CET 2009

But SAS/IML is not part of base SAS, it costs extra, so there is a good chance that a user that has SAS will not be able to run code that uses SAS/IML.

I have known of SAS programmers who know IML well that still write matrix/vector tools using macros or proc transpose so that a user without IML can still use the code (the fact that the code that started this thread was found on a website, suggests that it was meant for general use rather than something only used internally where you know what add-ons will be available).

Just another way that R makes life easier for both programmer and user.

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Gerard M. Keogh
> Sent: Friday, February 27, 2009 7:19 AM
> To: Frank E Harrell Jr
> Cc: r-help-bounces at r-project.org; R list
> Subject: Re: [R] Inefficiency of SAS Programming
> 
> Yes Frank, I accept your point but nevertheless IML is the proper place
> for
> matrix work in SAS - mixing macro-level logic and computation is
> another
> question - R is certainly more seemless in this respect.
> 
> Gerard
> 
> 
> 
>              Frank E Harrell
>              Jr
>              <f.harrell at vander
> To
>              bilt.edu>                 "Gerard M. Keogh"
>                                        <GMKeogh at justice.ie>
>              27/02/2009 13:55
> cc
>                                        R list <r-
> help at stat.math.ethz.ch>,
>                                        r-help-bounces at r-project.org
> 
> Subject
>                                        Re: [R] Inefficiency of SAS
>                                        Programming
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Gerard M. Keogh wrote:
> > Frank,
> >
> > I can't see the code you mention - Web marshall at work - but I don't
> think
> > you should be too quick to run down SAS - it's a powerful and
> flexible
> > language but unfortunately very expensive.
> >
> > Your example mentions doing a vector product in the macro language -
> this
> > only suggest to me that those people writing the code need a crash
> course
> > in SAS/IML (the matrix language). SAS is designed to work on records
> and
> so
> > is inapproprorriate for matrices - macros are only an efficient code
> > copying device. Doing matrix computations in this way is pretty mad
> and
> the
> > code would be impossible never mind the memory problems.
> > SAS recognise that but a lot of SAS users remain familiar with IML.
> >
> > In IML by contrast there are inner, cross and outer products and a
> raft
> of
> > other useful methods for matrix work that R users would be familiar
> with.
> > OLS for example is one line:
> >
> > b = solve(X`X, X`y) ;
> > rss = sqrt(ssq(y - Xb)) ;
> >
> > And to give you a flavour of IML's capabilities I implemented a SAS
> version
> > of the MARS program in it about 6 or 7 years ago.
> > BTW SPSS also has a matrix language.
> >
> > Gerard
> 
> But try this:
> 
> PROC IML;
> ... some custom user code ...
> ... loop over j=1 to 10 ...
> ...   PROC GENMOD, output results back to IML
> ...
> 
> IML is only a partial solution since it is not integrated with the PROC
> step.
> 
> Frank
> 
> >
> >
> >
> >
> 
> >              Frank E Harrell
> 
> >              Jr
> 
> >              <f.harrell at vander
> To
> >              bilt.edu>                 R list <r-
> help at stat.math.ethz.ch>
> 
> >              Sent by:
> cc
> >              r-help-bounces at r-
> 
> >              project.org
> Subject
> >                                        [R] Inefficiency of SAS
> Programming
> >
> 
> >              26/02/2009 22:57
> 
> >
> 
> >
> 
> >
> 
> >
> 
> >
> >
> >
> >
> > 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.
> >
> > Frank
> > --
> > Frank E Harrell Jr   Professor and Chair           School of Medicine
> >                       Department of Biostatistics   Vanderbilt
> University
> >
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> >
> >
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> 
> --
> Frank E Harrell Jr   Professor and Chair           School of Medicine
>                       Department of Biostatistics   Vanderbilt
> University
> 
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