BoxEdit stream not updating 2nd, 3rd ... box

[JanHomann]

Package versions

holoviews = 1.15.0
bokeh     = 2.4.3

Description of bug

When moving the 2nd, 3rd ... box liked to a BoxEdit stream, the plot generated by the callback function does not update the corresponding trace. The y-scale of the plot does get updated, though. When inspecting the BoxEdit element, it also contains the updated values.

This happens also (but not only) in the example provided by the official documentation:
https://holoviews.org/gallery/demos/bokeh/box_draw_roi_editor.html

Example code

Here is the official example code (link provided above), modified to work without the external data file dependency twophoton.npz.

import numpy as np
import holoviews as hv
from holoviews import opts
from holoviews import streams
hv.extension('bokeh')

data = np.random.randn(62,111,50)
calcium_array = data
ds = hv.Dataset((np.arange(50), np.arange(111), np.arange(62), calcium_array),
                ['Time', 'x', 'y'], 'Fluorescence')

polys = hv.Polygons([])
box_stream = streams.BoxEdit(source=polys)

def roi_curves(data):
    if not data or not any(len(d) for d in data.values()):
        return hv.NdOverlay({0: hv.Curve([], 'Time', 'Fluorescence')})
    
    curves = {}
    data = zip(data['x0'], data['x1'], data['y0'], data['y1'])
    for i, (x0, x1, y0, y1) in enumerate(data):
        selection = ds.select(x=(x0, x1), y=(y0, y1))
        curves[i] = hv.Curve(selection.aggregate('Time', np.mean))
    return hv.NdOverlay(curves)

hlines = hv.HoloMap({i: hv.VLine(i) for i in range(50)}, 'Time')
dmap = hv.DynamicMap(roi_curves, streams=[box_stream])

im = ds.to(hv.Image, ['x', 'y'], dynamic=True)
(im * polys + dmap * hlines).opts(
    opts.Curve(width=400, framewise=True), 
    opts.Polygons(fill_alpha=0.2, line_color='white'), 
    opts.VLine(color='black'))

Error message

No error message generated.

Bug in action

[JanHomann]

It seems like NdOverlay isn't correctly updating. I can't get Overlay to work, either.

[JanHomann]

This here works, but it requires fixing the number of elements in the NdOverlay beforehand. Unfortunately, this solution always generates a legend for ten elements. So it seems DynamicMap has a problem with a variable number of elements in the NdOverlay.

It seems like there was a similar issue already discovered, but closed as fixed: #3701

import numpy as np
import holoviews as hv
from holoviews import opts
from holoviews import streams
hv.extension('bokeh')

data = np.random.randn(62,111,50)
calcium_array = data
ds = hv.Dataset((np.arange(50), np.arange(111), np.arange(62), calcium_array),
                ['Time', 'x', 'y'], 'Fluorescence')

polys = hv.Polygons([])
box_stream = streams.BoxEdit(source=polys)

def roi_curves(data):
    # initialize NdOverlay with 10 empty curves
    ndoverlay = hv.NdOverlay({i:hv.Curve([], 'Time', 'Fluorescence') for i in range(10)}) #<---- line added
    if not data or not any(len(d) for d in data.values()):
        return ndoverlay                                                                  #<---- line changed
    
    data = zip(data['x0'], data['x1'], data['y0'], data['y1'])
    for i, (x0, x1, y0, y1) in enumerate(data):
        selection = ds.select(x=(x0, x1), y=(y0, y1))       
        s = selection.aggregate('Time', np.mean)        
        ndoverlay.get(i).data = s.data                             #<--- instead of making new curves, just change the data
    return ndoverlay                                               #<--- return NdOverlay

hlines = hv.HoloMap({i: hv.VLine(i) for i in range(50)}, 'Time')
dmap = hv.DynamicMap(roi_curves, streams=[box_stream])

im = ds.to(hv.Image, ['x', 'y'], dynamic=True)
(im * polys + dmap * hlines).opts(
    opts.NdOverlay(legend_position='right'),
    opts.Curve(width=400, framewise=True), 
    opts.Polygons(fill_alpha=0.2, line_color='white'), 
    opts.VLine(color='black'))

[droumis]

@philippjfr, do you think the first gif demonstrates a bug in HoloViews or Bokeh?

Also, as shown in the second gif, do think prepopulating the legend with empty entries is appropriate behavior in general?

[philippjfr]

Definitely a HoloViews bug, seems like elements in the NdOverlay that aren't rendered are still being considered in the range calculation of the overlay.

[JanHomann]

Seemed to have been fixed in holoviews = 1.15.4. Yay!

But now in holoviews = 1.16.2 the whole box_edit tool seems to be broken. It doesn't even show up in the toolbar, and when I add it by hand, it doesn't work. Not so yay.

[droumis]

I think there are multiple issues going on here. You can make the box_edit tool appear in the toolbar with opts(tools=['box_edit'].. but there's still a bug preventing this from working.. I think related to #5756

[hoxbro]

As @droumis said, it is a know regression because we changed from Bokeh's Rect to Bokeh's Quad. Quad currently does not support BoxEditTool, but should come in Bokeh 3.3, when this PR is merged bokeh/bokeh#13204.

[github-actions]

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