Controlling styling / modifications to D3FC charts

[limx0]

I'm currently streaming data from the tornado backend to a couple of perspective widgets in a html file (thank you for the plentiful examples!) one of which is a rolling time series scatter plot with multiple series. Currently, I believe, the mapping of colours/markers in the X/Y scatter plot is basically just the enumeration of whatever data exists in the table at a given time. This is causing my series to change colour/marker if one of the columns in the table is all null for some period of time. Is it possible to declare these styling attributes via some other config?

I wonder if it is within scope for perspective to allow configuring the plots from table values (for example like holoviews does - https://holoviews.org/user_guide/Style_Mapping.html)?

An example (the labels of L2 and L3 will flicker between orange and green depending on what is present in the data):

Set x-axis = timestamp, y-axis=value

import asyncio
import perspective
import random
import datetime

async def update(table):
    while True:
        now = datetime.datetime.now()
        data = [{"value": 1, "label": "L1", "timestamp": now}]
        for label in ("L1", "L2", "L3"):
            val = random.random()
            if val > 0.9:
                data.append({"value": val, "label": label, "timestamp": now})
        table.update(data)
        await asyncio.sleep(0.1)
        

schema = {
    "timestamp": datetime.datetime,
    'value': float,
    'label': str,
}

table = perspective.Table(schema, limit=10)
widget = perspective.PerspectiveWidget(table,  column_pivots=['label'], plugin="X/Y Scatter")
asyncio.get_event_loop().create_task(update(table))
widget # show

[limx0]

Hey @texodus - sorry for the tag but I see you've been hard at work on some UI improvements (which look awesome!) so I just wanted to bump and see if anything like this was on the radar (specifically more control over D3FC via table values ala holoviews Style Mapping link above)?

I could potentially offer a bounty for this work if that would help this along?

[texodus]

@limx0 there three conflated issues present we'd like to address:

1. Color range of "split_by" (formerly "column_pivots") shouldn't re-assign when the table is updated. This is a bug.
2. "X/Y Scatter" also has a color field (column position 3), so you could use "label" column here, but it does not currently work with string columns. However, "Treemap" and "Sunburst" do work correctly with string columns in the color field, so this is another easy bug.
3. We're working on a few UX features to specify the styling properties of charts, but this work is still in the design stage.

I've opened issues #2198 (1) and #2199 (2) to track these bugs, which should at least fix your issue for now, so I'm going to convert this issue to a discussion, in favor of those for tracking.