Holoviews: `hv.Layout` with `sizing_mode=scale_both` on its elements results in empty plot

[lsorber]

Let's say you want to create a responsive hv.Layout with tabs. If the elements of a hv.Layout have sizing_mode=scale_both (or any sizing_mode other than fixed for that matter), the resulting plot will be empty.

I suspect this is related to @philippjfr's comment (https://github.com/ioam/holoviews/issues/1230#issuecomment-289912599):

The thing is that a Layout does not determine it's own size, instead all the elements making up a Layout do.

Below is a minimal example that reproduces the problem:

import numpy as np
import holoviews as hv

scatter_plots = [
    hv.Scatter(
        (np.random.randn(10), np.random.randn(10)),
        label=str(i)).opts(
            plot={
                'width': 300,
                'height': 300,
                'sizing_mode': 'scale_both'  # [1]
            })
    for i in range(5)]

hv.Layout(scatter_plots).opts(
    plot={
        'tabs': True,
        'sizing_mode': 'scale_both'
    })

# Displays an empty plot unless [1] is set to 'fixed'.

[philippjfr]

In 1.12 we will be completely overhauling the layouts, at that point you can set responsive=True which will default to scale both behavior.

[lsorber]

Nice! Any estimate of when 1.12 would be ready for testing?

[philippjfr]

It's mostly waiting on bokeh 1.1.0 to be released, if you're happy to install a bokeh dev release you can play around with it on this branch https://github.com/pyviz/holoviews/pull/3450 right away.

[lsorber]

Now that Holoviews 1.12.1 is out, I tried it again with your suggestion and with some slight modifications it does seem possible to get responsive graphs, nice!

However, the behaviour of responsive=True does not seem to be aligned with sizing_mode='scale_both', which is defined as [1]:

Component will responsively resize to both the available width and height, while maintaining the original or provided aspect ratio.

If you try to set both a width and a height with responsive=True, you get several warnings that look like:

WARNING:param.PointPlot08998: responsive mode could not be enabled because fixed width and height were specified.

Does that mean there is currently no way to specify the aspect ratio of a responsive graph?

import numpy as np
import holoviews as hv

hv.extension('bokeh')

scatter_plots = [
    hv.Scatter(
        (np.random.randn(10), np.random.randn(10)),
        label=str(i)).opts(
            height=300,  # Setting a `width` as well fails
            responsive=True)
    for i in range(5)]

hv.Layout(scatter_plots).opts(plot={'tabs': True})

[1] https://bokeh.pydata.org/en/latest/docs/reference/models/layouts.html#bokeh.models.layouts.LayoutDOM.sizing_mode

[jbednar]

You should be able to specify the aspect or the data_aspect, depending on whether you want to specify the shape on the screen or the ratio of data values.

[lsorber]

Great, thanks @jbednar! With that, I think this issue can be closed.