Selection doesn't work with time variables

[sidravi1]

Hi,

The selection doesn't seem to work with time variable:

cars = data.cars.url

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

points = alt.Chart().mark_point().encode(
    x='Year:T',  # This is the only thing different from the example
    y='Miles_per_Gallon:Q',
    color=alt.condition(brush, 'Origin:N', alt.value('lightgray'))
).properties(
    selection=brush
)

bars = alt.Chart().mark_bar().encode(
    y='Origin:N',
    color='Origin:N',
    x='count(Origin):Q'
).transform_filter(
    brush.ref()
)

alt.vconcat(points, bars, data=cars)

Changing x to be "Horsepower:Q" in points works as expected

[jakevdp]

This is a known bug in vega-lite; see vega/vega-lite#3737

[jakevdp]

As a workaround, you can use a timeUnit: x=alt.X('Year:T', timeUnit='year')

[jakevdp]

Closing as a duplicate of #828

[sidravi1]

Thank you