[R-pkgs] homals package and core loop
Jan de Leeuw
deleeuw at stat.ucla.edu
Sat Sep 19 21:41:56 CEST 2009
The homals package
will get a major programming overhaul. This will take some time,
but what's a few years on a 40-year project. Suggestions
from the audience are welcome.
homals() has a core loop over the m variables in which
1. tapply is used to compute category quantification (centroids)
2. category quantifications are then adjusted to satisfy the
rank and level constraints
The idea is to replace 1 by least squares fitting of a B-spline and
to adjust 2 accordingly. The core will be re-programmed in C
and/or FORTRAN (sometimes using existing routines), and the loop over
variables will be parallelized using OpenMP or Grand Central Dispatch.
For ordinal variables this requires some alternative quadratic
routines to be linked in (which could then also become part of the
In addition the basic homals code will have object (individual) weights
(minor addition) and the prehom routines (from the jacobi package) will
be added. Because of the use of B splines the variables in homals will
no longer be all factors, some can now be numerical ("continuous").
Otherwise the package will keep its many analysis options (multi-set
non-metric canonical analysis,
non-metric discriminant analysis, non-metric regression, multiple
non-metric principal components analysis, non-metric additive conjoint
and its many plot options.
Jan de Leeuw, 11667 Steinhoff Rd, Frazier Park, CA 93225
home 661-245-1725 mobile 661-231-5416 work 310-825-9550
.mac: jdeleeuw +++ aim: deleeuwjan +++ skype: j_deleeuw
If I wanted you to understand it, I would have explained it
-- Johan Cruijff
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