Interactive layout fixes

[philippjfr]

The interactive layout was previously self-referential which causes issues when trying to display the plot/display component on its own. Additionally this ensures that a small fixes to assign a minimal height when no height is specified for the last item in a Column.

[jbednar]

Looks good. What does the representation of an interactive object look like now?

[jbednar]

Add a parameter default_height? Could be useful e.g. for the report mode dashboards...

[philippjfr]

Where would the parameter live, on Column? I'd be happy to add it but maybe in a separate PR.

[jbednar]

Well, height=50 is used here on Panel, so presumably on Panel, so that it can be height=self.default_height

[philippjfr]

It's specifically behind an isinstance check for Column to avoid having to duplicate the whole method there.

[philippjfr]

That said I could add an equivalent check for Row:

(isinstance(self, Row) and objects and not any(has_height(o) for o in objects))

[philippjfr]

Merging this, but I can follow up on this tomorrow.

[jbednar]

I'm seeing errors on this PR with "ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()" with https://anaconda.org/jbednar/datashadercliffordinteract/notebook

[philippjfr]

Not sure how that could be caused by this PR.

[jbednar]

Not sure either, just that it works with master (v0.2.0a4-1-ge98e151) and not with this branch (v0.2.0a4-6-g40bc2ba).

[philippjfr]

Looks like an issue in the repr.

[codecov-io]

Codecov Report

Merging #136 into master will increase coverage by 0.04%.
The diff coverage is 98.11%.

@@            Coverage Diff             @@
##           master     #136      +/-   ##
==========================================
+ Coverage   89.88%   89.92%   +0.04%     
==========================================
  Files          28       28              
  Lines        4181     4209      +28     
==========================================
+ Hits         3758     3785      +27     
- Misses        423      424       +1

Impacted Files	Coverage Δ
panel/util.py	80.64% <100%> (+1.33%)	⬆️
panel/tests/test_interact.py	100% <100%> (ø)	⬆️
panel/param.py	90.75% <100%> (+0.21%)	⬆️
panel/interact.py	71.42% <100%> (-0.28%)	⬇️
panel/pane.py	81.84% <100%> (ø)	⬆️
panel/viewable.py	69.26% <100%> (-0.28%)	⬇️
panel/layout.py	95.19% <92.3%> (+0.21%)	⬆️

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[jbednar]

This change really improved the usability of what's returned by interact(), and I've updated https://anaconda.org/jbednar/datashadercliffordinteract/notebook to reflect that. Now, the repr is something even more clear and clearly usable:

>>> i = pn.interact(clifford_plot, a=(-2,2), b=(-2,2), c=(-2,2), d=(-2,2), 
              n=(1,20000000), colormap=ps, panel_layout=pn.Row)
>>> print(i)


Column
    [0] WidgetBox
        [0] FloatSlider(end=2, name='a', start=-2, value=1.7)
        [1] FloatSlider(end=2, name='b', start=-2, value=1.7)
        [2] FloatSlider(end=2, name='c', start=-2, value=0.6)
        [3] FloatSlider(end=2, name='d', start=-2, value=1.2)
        [4] IntSlider(end=20000000, name='n', start=1, value=2000000)
        [5] Select(name='colormap', options={'bgy': ['#fff123', ...}, value=['#b3fef5', '#b0fef5', ...])
    [1] Row
        [0] PNG(Image, name='interactive00026')

So it's now obvious that one can do pn.Column(i[0][5], i[1][0]) to get a column with just the Select widget above the PNG image, with no opaque interact objects. Very nice!