Weitghed contingency tables

[lluritu]

Hello, when computing gridded verification metrics and aggregating over a spatial domain it is sometimes important to weight the contributions of each grid point by the area it represents. However, all the scores based on the contingency table do not offer this option in xskillscore.

Recently I prepared a modification of the contingency tables code that allows weighting the counts by the cos(lat) of the (regular lat-lon) gridded data. Since xhistogram supports weights, it is a relatively simple implementation.

If that is of general interest, please let me know and I can contribute the code.

Best,
Llorenç

[aaronspring]

Great. Please open a PR