indexes section in the HTML repr

[keewis]

To see the effect, try this:

import xarray as xr
from xarray.core.indexes import Index


class CustomIndex(Index):
    def __init__(self, names, options):
        self.names = names
        self.options = options
    
    @classmethod
    def from_variables(cls, variables, options):
        names = list(variables.keys())
        
        return cls(names, options)
    
    def __repr__(self):
        options = (
            {"names": repr(self.names)}
            | {str(k): str(v) for k, v in self.options.items()}
        )
        
        return f"CustomIndex({', '.join(k + '=' + v for k, v in options.items())})"

    def _repr_html_(self):
        header_row = "<tr><td>KDTree params</td></tr>"
        option_rows = [
            f"<tr><td>{option}</td><td>{value}</td></tr>"
            for option, value in self.options.items()
        ]
        return f"<left><table>{header_row}{''.join(option_rows)}</table></left>"

ds = xr.tutorial.open_dataset("rasm")
ds1 = ds.set_xindex(["xc", "yc"], CustomIndex, param1="a", param2="b")

with xr.set_options(display_style="text"):
    display(ds1)

with xr.set_options(display_style="html"):
    display(ds1)

The repr looks a bit strange because I've been borrowing the variable CSS classes. Edit: @benbovy fixed that for me

Also, the discussion about what _repr_inline_ should include from #7183 is relevant here as well.

• Follow-up to display the indexes in the string reprs #6795, depends on use _repr_inline_ for indexes that define it #7183
• Tests added
• User visible changes (including notable bug fixes) are documented in whats-new.rst

[benbovy]

Thanks @keewis for opening this PR.

I added some commits (hope you don't mind) to fix the CSS. I also grouped the items in the indexes section by unique index with index coordinates separated by line return, so it looks like the coordinate section while the multi-coordinate indexes are clearly visible.

[keewis]

I added some commits (hope you don't mind) to fix the CSS

thanks a lot for that, @benbovy, I wouldn't have been able to figure that out on my own since my knowledge of CSS is pretty limited.

[benbovy]

LGTM, that's awesome! It will be super handy for quick debugging and experimenting with custom indexes.

[benbovy]

🚀