Re: moving coefficient.[ch] and design-matrix.[ch]

[John Darrington]

I'm worried that src/data is becoming a dumping ground for things
which don't fit elsewhere.  At the same time, src/math is becoming
depleted.

I always envisaged src/data to be about the definition, storage and 
access of data.  The manipulation of data is, as I see it, a seperate,
higher level task.

J'

On Tue, Jun 10, 2008 at 01:45:30PM -0400, Jason Stover wrote:
     I want to move coefficient.[ch] and design-matrix.[ch] to
     src/data. Ben and I thought this might be a good idea after discussing
     it on IRC, so I thought I would elicit more discussion here.
     
     coefficient.[ch] and design-matrix.[ch] don't do any computations.
     They're purpose to offer some common, data-shuffling functionality to
     model-fitting procedures in src/math/. Right now the only
     model-fitting code in src/math is linreg, but we will eventually want
     code for logistic regression and other models. They all need design
     matrices and coefficients to match variables to columns to
     coefficients. That matching goes pretty much the same for each kind of
     model.
     
     So it seems that a model-fitting directory in src/math should depend
     on coefficient.[ch] and design-matrix.[ch]. coefficient.[ch] and
     design-matrix.[ch] probably should not have to know about
     model-fitting: there are many kinds of models, and for each of them, a
     coefficient means the same thing, and a design matrix means the same
     thing, independently of what kind of model it is.
     
     Furthermore, coefficients and design-matrix code doesn't have any math
     in it. There is no linear algebra, or descent algorithms, etc. That
     code just takes a coefficient and returns the variable it matches, or
     vice versa, or takes a variable and finds its corresponding columns in
     a design matrix.  So putting this in src/math doesn't seem as
     appropriate as putting it in a place like src/data.
     
     coefficient.c depends on linreg.h, but that could be changed. By contrast,
     design-matrix.c depends on src/data/category.h, and I don't think I could
     eliminate this dependency.
     
     So how does everyone feel about moving coefficient.[ch] and
     design-matrix.[ch] to src/data? If it sounds good, I'll post a patch.
     
     -Jason
     
     
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