norm framewise broken for Overlays inside DynamicMaps

[basnijholt]

Take this function

offset = 0


def plot_generator(overlay):
    global offset
    while True:
        ys = np.random.rand(10) + offset
        offset += 0.1
        if overlay:
            yield hv.Curve(ys) * hv.Scatter(ys)
        else:
            yield hv.Curve(ys)


get_dm = lambda overlay: hv.DynamicMap(
    plot_generator(overlay), streams=[hv.streams.Stream.define("Next")()]
).opts(norm=dict(framewise=True))

Now everything is fine like this:

dm = get_dm(overlay=False)
dm

dm.periodic(0.5)  #next cell

gives:

But when there is an overlay, it doesn't work:

dm = get_dm(overlay=True)
dm

dm.periodic(0.5)  #next cell

gives:

This blocks python-adaptive/adaptive#186.

[jbednar]

Overlays do not currently support normalization options. I propose that an Overlay have framewise=None by default, and if it's set to True it would behave like .map(lambda obj: obj.opts(framewise=True), hv.Element). I think the semantics of that are clear, though @philippjfr indicates it won't be very straightforward to implement.

Given that Overlay is a type of Layout, it may make sense to do this at the Layout level, as people presumably would want to set the options on Layouts as well. In that case we can also consider whether axiswise=True should behave the same. I think so, but haven't thought deeply about it.

[holovizbot]

This issue has been mentioned on HoloViz Discourse. There might be relevant details there:

https://discourse.holoviz.org/t/cant-independently-set-the-xlim-of-plot-in-a-layout/8974/5