Is highlighting/selection not working for `varea` (or `varea_stack`)?

[erich]

What are you trying to do?

I am trying to link the selection from stacked_varea plot to a DataTable widget
i.e. the selection from any one side will be hightlighted on the other widget

What have you tried that did NOT work as expected?

What I have tried

I have tried to convert the “data_table_plot” example from a scatter plot to a stacked varea plot

the “data_table_plot” example:

data_table_plot

What is not working

• selection does not seem to work in the (stacked_area) plot
• if selection is made in the DataTable widget, it does not reflect (highlight) on the plot widget

A minimal, reproducible example:

from bokeh.layouts import column
from bokeh.models import (
    ColumnDataSource,
    DataTable,
    HoverTool,
    IntEditor,
    NumberEditor,
    NumberFormatter,
    SelectEditor,
    StringEditor,
    StringFormatter,
    TableColumn,
)
from bokeh.plotting import figure, show
from bokeh.sampledata.autompg2 import autompg2 as mpg

source = ColumnDataSource(mpg)

manufacturers = sorted(mpg["manufacturer"].unique())
models = sorted(mpg["model"].unique())
transmissions = sorted(mpg["trans"].unique())
drives = sorted(mpg["drv"].unique())
classes = sorted(mpg["class"].unique())

columns = [
    TableColumn(
        field="manufacturer",
        title="Manufacturer",
        editor=SelectEditor(options=manufacturers),
        formatter=StringFormatter(font_style="bold"),
    ),
    TableColumn(field="model", title="Model", editor=StringEditor(completions=models)),
    TableColumn(
        field="displ",
        title="Displacement",
        editor=NumberEditor(step=0.1),
        formatter=NumberFormatter(format="0.0"),
    ),
    TableColumn(field="year", title="Year", editor=IntEditor()),
    TableColumn(field="cyl", title="Cylinders", editor=IntEditor()),
    TableColumn(
        field="trans", title="Transmission", editor=SelectEditor(options=transmissions)
    ),
    TableColumn(field="drv", title="Drive", editor=SelectEditor(options=drives)),
    TableColumn(field="class", title="Class", editor=SelectEditor(options=classes)),
    TableColumn(field="cty", title="City MPG", editor=IntEditor()),
    TableColumn(field="hwy", title="Highway MPG", editor=IntEditor()),
]
data_table = DataTable(
    source=source,
    columns=columns,
    editable=True,
    width=800,
    index_position=-1,
    index_header="row index",
    index_width=60,
)

p = figure(
    width=800,
    height=300,
    tools="pan,wheel_zoom,xbox_select,reset",
    active_drag="xbox_select",
)

p.varea_stack(
    stackers=["cty", "hwy"],
    x="index",
    source=source,
)


show(column(p, data_table))

Related issues

I have read from other post that a line is render as a single glyph, so no individual data point glyph can be selected.
I would guess area is render similarly?

How to highlight selected area when using Line glyph?

When I use the Circle glyph, the data points that are included in the selected area (using the BoxSelectTool) are being highlighted automatically. When I switch to the Line glyph nothing happens. How can I highlight the selected area of a line and get the selected data points?

However, the docs of varea https://docs.bokeh.org/en/latest/docs/reference/plotting/figure.html#bokeh.plotting.figure.varea

also said

It is also possible to set the color and alpha parameters of extra glyphs for selection, nonselection, hover, or muted. To do so, add the relevant prefix to any visual parameter. For example, pass nonselection_alpha to set the line and fill alpha for nonselect, or hover_fill_alpha to set the fill alpha for hover. …

so I am a bit confused.

another possibily related issue
https://discourse.bokeh.org/t/how-to-highlight-a-selected-area-in-the-graph-and-finding-max-min-values-with-using-bokeh/9276

Thank you in advance.
(There is a 2 link max. limit for new users, so unfortunately have to put some links as raw literal to work around it.)

[Bryan]

Not all glyphs support all kinds of hit-testing. E.g. varea only supports “point” hit testing, so it will only register selections from “point” events (i.e. clicking, mouse-hover). So xbox_select is not going to do anything with varea. Full details are in the wiki:

Glyph Hit Testing Census

It’s possible that glyph support for different hit-testing modes expands over time, but that would be future development.

[erich]

icic, thanks for the explanation.