S-plus and Grass

Gillian Bowser gillian at rmro.nps.gov
Mon Jul 17 08:00:00 EDT 1995

My experience with splus is limited, but I thought you might
be vaguely interested in some of my thoughts.

1. Interface with Grass.
I found with my datasets (path lengths from v.line/r.drain/r.cost),
it was easier to slam-dunk the data through a nawk shell script
than trying to convince splus that my column headings were important.
I currently use a series of scripts to strip off any unnecessary muck
that comes from the output of the v.line and I place tabs between all
columns and create headers (names files to splus).  Works pretty slick and
seems to give me alot more manoverability than dealing with sites files.

2. Spatial Statistics
Splus is sorely lacking in both spatial statistics (morans, kriging, etc.)
and in cluster analysis (WPGMA, UPGMA, etc.).  The cluster diagrams are
pretty poor compared to SYSTAT and I don't know how to get the cophenetic
matrix out of splus (might be missing something obvious...).  I also find
the discussion of autocorrelation to be limited (actually they mainly discuss
serial correlation in the sense of time series and really don't address
spatial autocorrelation at all).

3. Parametric statistics
Regression analysis appears to be stubborn.  I have not currently had
luck with changing the order things go into a multiple regression
(akin to stepwise foward/backward).  Again, I have bailed to running
a shell script to rearrange my database, then bring the new database in 
and try again.

4. Odd-ball problems
Splus has an unpleasant habit of saving all sorts of tidbits in various
hidden locations. The number of tmp files created can be overwhelming--although
fixable with a function (the documentation of the function "on.exit" is
horrible).  I also find it annoying that some terms that splus happily uses
I can't locate in any of my statistics books.

In sum, I am stuck with splus because it is the only package on our
system.  I have used SYSTAT, SAS, BMDP, JMP, and various other packages 
and am afraid to say that splus ranks towards the bottom.  FOr example, I
output data, after testing it in splus (and getting all the sexy graphics),
to a pc with SYSTAT to run Moran's I or to get a lollipop diagram of
cluster data (and the cophenetic matrix). To test the spatial autocorrelation
of the database, it is currently easier to telnet to a system with SAS on it
and have someone run the data than to deal with splus.

As someone in our office exclaimed laughing: "This fancy (expensive) program
on our UNIX net was just beat out by a MAC (a LC40 mac even)???", the sad truth
is that splus does a nifty job on graphics, but as an interface to spatial
databases, I cannot for the life of me, figure out why they don't cover
spatial statistics, autocorrelation, Moran's Index, kriging, ansiotrophy,

I would be most interested in any summary as splus is an ongoing headache for

Gillian Bowser
Resource Management Specialist
National Park Service-Rocky Mountain Support Office
Denver, Colorado

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