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Add Poisson likelihood fitter #1056
Description
I would like to add a PoissonLikelihoodFitter as available e.g. in Sherpa (described here) to be able to fit Poisson count data.
A preliminary version can be found here: class, example.
TODO:
- Make it work with n-dimensional models and data (currently only supports 1-dimensional)
- Pass extra arguments along to
scipy.optimize.minimize. - Is this the right way to handle integral models?
cc @nden, @embray Should I try to implement this now and get it into astropy or should I wait for your modeling APE and further structural changes in astropy.modeling?
EDIT: the issue description was updated, so some comments below are outdated / irrelevant now.
Activity
eteq commentedon May 6, 2013
I don't know if we ever fully specified a version. It's already an "optional" dependency, so using whatever version makes sense is fine.
Probably the best thing to do is a
try/exceptinside the function that explicitly states something like "Scipy 0.11 is needed for custom fit functions"cdeil commentedon Oct 19, 2013
Here's a first prototype version: http://nbviewer.ipython.org/7062154
that I managed to write thanks to @nden's example here: https://gist.github.com/nden/5466946
@nden At the moment to create a user-defined fitter one has to add to the
constraintsdefdict (or the Fitter initialisation will fail in the_constraintscheck):I guess this shouldn't be needed?
If it is, it should be described here.
embray commentedon Oct 23, 2013
Nice. I do think there are some areas where defining a new fitter could be easier. I have a note somewhere, for example, that the
constraintsdefdict shouldn't be used explicitly anywhere, and that the purpose it serves could be handled automatically by aFittermetaclass and a couple class attributes. We'll see if I get to that. Defining theerrorfunccould be a bit easier too. But overall it looks like that was pretty easy.cdeil commentedon Oct 24, 2013
+1 to removing the global
constraintsdefdict and storing this info in classes.embray commentedon Oct 24, 2013
Done in 3552d36
astrofrog commentedon Jan 14, 2015
+1 to the idea, but removing 1.0 milestone
cdeil commentedon Mar 2, 2016
We're using Sherpa now, so we don't need this in Astropy any more and I don't plan to work on it there.
Closing this old issue.
embray commentedon Mar 2, 2016
Would rather leave issues like this open--just because you don't need it or plan on working on it for Astropy doesn't mean it's not a good issue to keep open.
[-]WIP: Add Poisson likelihood fitter[/-][+]Add Poisson likelihood fitter[/+]cdeil commentedon Mar 2, 2016
An issue is mainly useful if there's a chance that it leads to improvements, right?
If it's just a bunch of year-old and outdated discussion keeping it open and making people re-read through it is just annoying.
In this case if someone is interested to implement this in astropy.modeling, they should ignore the discussion here and continue with #3786 .