[pymvpa] Generating more 'realistic' test data?

Yaroslav Halchenko debian at onerussian.com
Thu Sep 4 14:18:11 UTC 2014

On Wed, 03 Sep 2014, Shane Hoversten wrote:

>    Hi -
>    The data_generators module
>    ([1]http://www.pymvpa.org/generated/mvpa2.misc.data_generators.html) has
>    lots of methods to generate various flavors of test data, but the ones I
>    actually understand seem to produce a rather simple sort of multivariate
>    data, where differences between classes are characterized by modifications
>    to a single diagnostic nonbogus feature for each class, s.t. that single
>    diagnostic voxel has a larger mean.
>    I'd like to do something like generate data where condition A lives in
>    some subspace of the feature space, and condition B lives in another
>    subspace, where the subspaces can span larger regions than the 2d ones
>    like in pure_multivariate_signal; or live on a certain simplex; or
>    something else where classes live within a more sophisticated
>    high-dimensional decision boundary.
>    It's possible that such a thing can be assembled with the tools already
>    there and I just don't see how; if so, can someone suggest how it might be
>    accomplished?  Or is this a weird-enough thing to want that I need to roll
>    my own?

Hi Shane

This is an interesting question and would be a very useful addition
happen someone comes up with a generalization for simulating more
of interesting multivariate signals.

I also apparently sent out a PR a while back
which moved one more function under data_generators from tests if you
are interested in simulating "realistic'ish fMRI" signal.

I see that I could possibly use get_random_rotation to move patterns
from a "simple sort of multivariate" to at least somewhat more

overall -- we would welcome PRs for new data generators or tuneups to
existing ones.  Or if you come up with an independent library -- please
let us know please

Yaroslav O. Halchenko, Ph.D.
http://neuro.debian.net http://www.pymvpa.org http://www.fail2ban.org
Research Scientist,            Psychological and Brain Sciences Dept.
Dartmouth College, 419 Moore Hall, Hinman Box 6207, Hanover, NH 03755
Phone: +1 (603) 646-9834                       Fax: +1 (603) 646-1419
WWW:   http://www.linkedin.com/in/yarik        

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