[SciPy-Dev] scikit-procrustes

Melissa Weber Mendonça profamelissa at gmail.com
Tue Aug 29 10:21:59 EDT 2017


In general, in unbalanced problems you are looking for a solution with more
rows than columns (i.e. more data than variables, in the statistical
sense). So the problem does not have a closed form solution, but needs to
be solved via iterative methods. The balanced case is solved by performing
one SVD, and the unbalanced problem needs roughly one SVD per iteration,
and in ill conditioned problems this might mean a large number of SVD's.

Together with a colleague we have studied a new method for this (cited in
the docs), and I had to test it against other previously developed methods,
so I had to implement the scikit for my research purposes. From what I
gather, in Psychometrics it might be useful to use the unbalanced problem
if you are looking to find redundancies in the variables, for example.

- Melissa

Em ter, 29 de ago de 2017 às 11:02, Scott Sievert <sievert.scott at gmail.com>
escreveu:

> How is the unbalanced problem different, and what applications does it
> have? I've used the Procrustes transform for some low dimensional embedding
> problems, and I'm curious to hear.
>
> Scott
>
> On Aug 29, 2017, 8:33 AM -0500, Melissa Weber Mendonça <
> profamelissa at gmail.com>, wrote:
>
> Hello everybody,
>
> My name is Melissa, I'm a professor and researcher at the Federal
> University of Santa Catarina, in Brazil. I'm an applied mathematician
> working with Numerical Optimization and I've been working for some time
> with Procrustes Problems. So I realized there was no implementation of
> methods to solve the unbalanced Procrustes problem in python, and I decided
> to build a scikit. Here it is:
>
>
>    - https://github.com/melissawm/skprocrustes
>
>
> http://scikits.scipy.org/scikit-procrustes
>
> All are welcome to criticize and to send pull requests if you feel you
> have something to contribute, I'd appreciate it. I hope this is useful for
> someone.
>
> Cheers!
>
> Melissa
>
> p.s. I'm not an expert in packaging and so it's highly possible that my
> code is not optimal, if you have any suggestions I'd appreciate as I'm
> trying to get better at this :)
>
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