Attach ScaleBar to subcoordinate axis

[droumis]

Allow adding scale bars to individual subplot/subcoordinate_y ranges. The current implementation only allows for a scale bar to be positioned relative to the entire plot. This depends on progress in Bokeh: bokeh/bokeh#13921

A possible API might be to use a new arg; something like scalebar_level="subcoordinate_y"

Code

import holoviews as hv
import numpy as np
hv.extension("bokeh")

# scalebar_level="subcoordinate_y")

common_opts = dict(subcoordinate_y=True, scalebar=True, scalebar_range='y', scalebar_unit=('cm', 'm'),)

c1 = hv.Curve(np.random.rand(1000), label='c1').opts(color='lightblue',  scalebar_location="left", scalebar_opts={'bar_length':.1, 'background_fill_alpha': .2, 'bar_line_color':'darkblue'}, **common_opts)
c2 = hv.Curve(np.random.rand(1000), label='c2').opts(color='indianred', scalebar_location="bottom_right", scalebar_opts={'bar_length':.1, 'background_fill_alpha': .2, 'bar_line_color':'darkred'}, **common_opts)
c3 = hv.Curve(np.random.rand(1000), label='c3').opts(color='plum', scalebar_location="top_left", scalebar_opts={'bar_length':.1, 'background_fill_alpha': .2, 'bar_line_color':'purple'}, **common_opts)
c4 = hv.Curve(np.random.rand(1000), label='c4').opts(color='palegreen', scalebar_location="right", scalebar_opts={'bar_length':.1, 'background_fill_alpha': .2, 'bar_line_color':'darkgreen'}, **common_opts)

curves = hv.Overlay(c1 * c2 * c3 * c4).opts(show_legend=False)
curves.opts(width=800, height=600)

Arrows indicate where the scale bars should be after applying to subcoordinate level:

[droumis]

@hoxbro , this is unblocked now with bokeh/bokeh#14005

[hoxbro]

It is not unblocked, e.g., I can't do any development in HoloViews yet.

Did you mean that progress has been made?

[droumis]

If that PR is functionally ready, can't we start exploring how it can implemented in HoloViews?

[droumis]

discussion: dev release of Bokeh 3.6, then dev release of Panel (supporting Bokeh 3.6) needed prior to doing any HoloViews work on this

check in ~2 weeks