update_*() batch methods

[nicolaskruchten]

Given that px produces figures which often have non-trivial numbers of fairly 'regular' axes/annotations/traces, it would be very convenient to have something like Figure.update_traces( <patch>, <selector> )-type methods e.g.

px.scatter(..., marginal_y="violin").update_traces(
    patch=dict(marker_line_color="black"), 
    selector=dict(type="scatter")
)

In this example, px.scatter() generates some scatter traces but also some violin ones, so the patch will only apply to the scatter traces. Also note that this example uses some magic-underscores from #1481

This would also be very convenient for changing axis-level attributes in the case of a facetted px plot with many axes, ditto the annotation-based facet titles etc. In fact, I could see this being useful pretty much anywhere we have a collection of things either in a list (annotations, traces, shapes, etc) or with a number suffix (xaxis, yaxis, geo, scene, etc).

A more uniform API where all the method are called batch_update like Figure.data.batch_update() or Figure.layout.xaxis.batch_update() might work as well? The latter case maybe less nice, but there is no "collection" of x-axes on which to attach the method there :)

[jonmmease]

I like it. Here are some places that come to mind where I can see this being immediately useful.

fig.update_traces()
fig.layout.update_xaxes()
fig.layout.update_yaxes()
fig.layout.update_geos()
fig.layout.update_polars()
fig.layout.update_scenes()
fig.layout.update_annotations()
fig.layout.update_shapes()

parcoords.update_dimensions()
parcats.update_dimensions()

Another option, would be to support JSONPath-style keys in the existing .update method (See https://github.com/json-path/JsonPath#path-examples).

# Update marker line color of all scatter traces
fig.update({'data[?(@.type == 'scatter')].marker.line.color': 'green'})

# Update colorbar title font family across all colorbars, and all nesting levels
fig.update({'..colorbar.title.font.family': 'Rockwell'})

This would offer pretty complete flexibility, at the cost of perhaps a slightly higher learning curve. I'm also not sure how much we could reuse from existing libraries like https://github.com/kennknowles/python-jsonpath-rw.

[nicolaskruchten]

I think the JSONPath idea is a good one, but likely not a total replacement for either what I'm proposing here or magic-underscores...

One other thing I want to throw into the mix is a more swiss-army-knifey for_each_trace(callback, selector) variant (which could be used internally in combination with the normal .update(patch) methods to build update_traces(patch, selector)) that would allow for people to write more complicated logic like uppercasing trace names or whatever.

[jonmmease]

Merged in #1534. It's not everything discussed in this issue, but it's the things that motivated the initial use case so I'm going to close this. We can open a new issue if there are chunks here that warrant further discussion.

[nicolaskruchten]

For real px customizability we will need easy ways to batch-update xaxis and yaxis... If you facet and want to format your ticks you'll need to update multiple axes, unless we add another match-style attr in the JS layer that matches all formatting attributes across axes as well as range (which is not a bad idea actually), and then people could just update xaxis and yaxis. hmmm :)

[jonmmease]

For real px customizability we will need easy ways to batch-update xaxis and yaxis

You're right. Done in #1548