Add finding largest closed contour for PDFs

[e-koch]

• Find largest closed contour for given map
• Allow passing a custom mask to get PDFs of sub-regions
• Add to tutorial page and describe how custom masking should be done (e.g., with spectral-cube)

[keflavich]

This has to be built into the contour finding algorithms already, right? They must be making a choice somewhere about whether or not to draw a line, and at map edges, that choice is 'no'. So it should hopefully be easy to find.

[low-sky]

I've done this by finding the contours in matplotlib and testing if high point is inside. Sent from a mobile device. Please excuse brevity.

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On Jul 11, 2017, at 16:50, Adam Ginsburg ***@***.***> wrote: This has to be built into the contour finding algorithms already, right? They must be making a choice somewhere about whether or not to draw a line, and at map edges, that choice is 'no'. So it should hopefully be easy to find. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub, or mute the thread.

[e-koch]

I think so. We're already using some of the mpl contour backend for PCA: https://github.com/Astroua/TurbuStat/blob/master/turbustat/statistics/pca/width_estimate.py#L153. Maybe starting the search at the maximum along the edge would be efficient. Though there should be some minimum size requirement for the region along the edge too.