Selection Chart can't run independently

[diegomarvid]

I have the following code for displaying the data:

brush = alt.selection(type='interval')

points = alt.Chart(houses_prices).mark_point(opacity=0.2).encode(
    x='id:Q',
    y='SalePrice:Q',
    color=alt.condition(brush, alt.value('blue'), alt.value('lightgray'))
).add_selection(
    brush
)

qual = alt.Chart(houses_prices).mark_bar().encode(
    alt.Y('OverallQual:N', axis=alt.Axis()),
    x='count(OverallQual):Q'
).transform_filter(
    brush
)

points & qual

house_prices is a pandas DataFrame.

This code runs well and produces the following output:

However I want the possibility to run points and qual separately. If I run qual on its own (with points initialized) the following error ocurres:

I would like this functionality because if I have lots of selections, the way they are displayed has to be more carefully.

[joelostblom]

It is because you have added the selection only to the points chart. qual.add_selection(brush) should work in a new cell.

[diegomarvid]

It is because you have added the selection only to the points chart. qual.add_selection(brush) should work in a new cell.

It doesn't produce any error but the chart doesn't update in realtime as selection in points varies

[jakevdp]

Altair doesn't provide any facility to link selection behavior between different charts. If you want that behavior, you have to concatenate them into a single chart.

I believe that what you want to do can be done with vega-level signals implemented in JavaScript, but I don't know of any examples of doing it.

[joelostblom]

Selections only work on objects in the same Altair/VegaLite view. If you display the charts separately, then selections in the points chart will not update the qual chart.

[diegomarvid]

I understand. I don't know how easy or hard would be to enable that functionality in the library or if more people find it useful. I will not try to display them separetely if the library doesnt allow that. Thanks for your time.