Styles going missing when slicing NdOverlays

[jlstevens]

In my work, I am generating an NdOverlay where the individual curves are customized by color:

traces = NdOverlay({float(c):Curve(d)(style={'color':col}) 
                    for c,(d, col) in data.items() }, kdims=['Contrast'])

The result has the colors I would expect but it seems the color settings are lost if I slice the NdOverlay. For instance, if I do traces[3.1:,:] to eliminate the 3% contrast trace, the NdOverlay seems to revert back to the default color cycle.

Edit: Fixed example.

[philippjfr]

Wait I'm assuming that was a mistake but isn't the call in your example, i.e. traces() doing the clearing? Did you mean to do that or is there an actual bug if you get rid of the call?

[jlstevens]

Yes sorry! Ignore the call (fixed above in an edit)

[philippjfr]

Hmm, this is a more general problem to do with inheritance of the id attributes. By default the id is currently not inherited when performing a clone operation and since the __getitem__ just uses clone internally that is what happens. Should all clone operations inherit the id? If so this is an easy fix.

[philippjfr]

As I said above this is not actually a bug, it's expected behavior. The question is do we want to change it? You could have avoided this issue altogether if you sliced only the NdOverlay not the Curves themselves, i.e. this traces[3.1:] instead of this traces[3.1:,:].

[jlstevens]

I see what you mean now and I do think it is fairly confusing behavior. As a result, I think copying the ids across might be a good idea although I'll need time to think through all the possible consequences of this...

[philippjfr]

This now works as you expected:

traces = hv.NdOverlay({col:hv.Curve(np.random.rand(10,2))(style={'color':col}) 
                       for i, col in enumerate(['red', 'green', 'blue']) }, kdims=['Contrast'])
traces[['red', 'green'], :]

Closing.