opts magic inheritance cmap

[marqh]

import iris
import holoviews as hv
import geoviews as gv
import cube_browser
import cartopy

cube = iris.load_cube(iris.sample_data_path('rotated_pole.nc'))

with a specification of Dataset, the color map is preserved:

%%opts FilledContours.Air_pressure_at_sea_level [levels=7]

airp = hv.Dataset(cube)
airp.to.filledcontours(['grid_longitude', 'grid_latitude'], dynamic=True)  * gv.Feature(cartopy.feature.COASTLINE)

but, if the FilledContours does not specifiy the Air_pressure...., the colormap is overridden

%%opts FilledContours.Air_pressure_at_sea_level [levels=7]

airp = hv.Dataset(cube)
airp.to.filledcontours(['grid_longitude', 'grid_latitude'], dynamic=True)  * gv.Feature(cartopy.feature.COASTLINE)

this last call should not alter the colormap

[philippjfr]

I can't tell the difference between your two examples. Presumably you meant:

%%opts FilledContours [levels=7]

in the second example. If so that's a bug propagating the custom options correctly and probably originates in the StoreOptions.create_custom_trees method. I'll assign it to @jlstevens.

Edit: Just went through the logic in that method and as far as I can tell it definitely originates there. It creates a new custom tree using the specification passed in via the magic rather than traversing the object to get the full type.group.label spec of all the Elements that the custom options apply to. So it ends up making a copy of the options.FilledContours node rather than copying the options.FilledContours.Air_pressure_at_sea_level which holds the colormap setting.

[bjlittle]

@jlstevens says: yes, it is fine to assign it to him and you are right that the example is wrong (your version is right)

[philippjfr]

It's a pretty tricky problem and I know roughly how to fix it but actually implementing the correct solution will still be pretty difficult. Hopefully @jlstevens will have the time to tackle it this week, otherwise I'll try to spend an hour or two on it over the weekend.

[philippjfr]

This has finally been fixed in #796. Closing.

[github-actions]

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