how to change HLine's axis range

[cocoaaa]

Hi,
What is a recommended way to set the axis range of HLine objects?
The three methods recommended In #1717 doesn't work on HLine object. My guess is that this is because HLine and Curve are semantically different: HLine is considered a function defined on all real values whereas Curve is defined on the range specified in the user's input data. Please correct me if that's not the reasoning behind it. For HLine objects, then, how can I change the ylim range (eg. using the redim method)?

Here are my quick test cases. It seems to work with only matplotlib as the backend, not bokeh, which seems to be aligned with bokeh's API, but the option of ylim appears on the auto-tabcomplete of HoloViews.

Another strange behavior is that the backend keyword inside (object).opts doesn't override the option set by hv.extension method. I would expect this to override the backend option for the caller object. Could you clarify if this is an intended outcome?

Slightly different, but related question is, is it possible to set a default figure size (height and width) using %%opts or opts.defaults method without specifying the element type?

Thanks!

[jbednar]

If you want the line to have a specific extent, usually you would use hv.Path(). hv.HLine is for annotating other plots, where it is not intended to modify the other plot's extents.

The backend keyword in .opts() declares which backend the options are to be applied to, for cases where the same object can be customized appropriately for multiple backends. But this is a declaration only; it does not actually force the object to be displayed with any particular backend when it is later shown. I wish we could make that behavior more obvious somehow, but I can't think how to make that clearer.

[cocoaaa]

Thank you for your quick response.
I thought hv.HLine would be the right type to use if I wantto add a horizontal line to a figure of Curve. I noticed that the container object (eg. curve * hline)'s ylim can be modified via opts(ylim=(a,b)) and was expecting the same would work for hv.HLine element:

Just sharing what I was expecting as a user:)
I guess in most cases, though, people wouldn't really draw a single horizontal but would overlay it to another figure.

[jbednar]

It was certainly the intention that an HLine would only be used as an overlay on other data, but it would still be nice if we could make it behave more intuitively when used on its own, so that people could go naturally between overlaid and non-overlaid contexts. Unfortunately, a lot of how it works is inherited from Bokeh and difficult for us to change, but other HoloViews developers may be able to suggest ways we can make it work in a less surprising way.

[cocoaaa]

I see. Another good feature would be to have the axis ranges automatically reset so as to it shows all elements involved. In the first figure above, for example, the container's ylim doesn't consider HLine element's range. Is this already implemented in HoloViews?

[jbednar]

Again, HLine's extents are deliberately not considered when setting ranges. E.g. one might put an annotation for "absolute upper limit", which should show if that value is ever reached, but isn't relevant otherwise. Annotations aren't meant to be used as data, but in principle we could add additional elements that look like the annotations but do behave like data, add an option to the annotation to make it act like data, or something of that sort...

[philippjfr]

This can be controlled by setting .opts(apply_ranges=True).

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