The Altair Notebook - Site title

import altair as alt
from vega_datasets import data

cars = data.cars()

interval = alt.selection_interval()

scatter = alt.Chart(cars).mark_point().encode(
    x='Horsepower:Q',
    y='Miles_per_Gallon:Q',
    color=alt.condition(interval, 'Origin:N', alt.value('lightgray'))
).add_selection(
    interval
)

hist = alt.Chart(cars).mark_bar().encode(
    x='count()',
    y='Origin',
    color='Origin'
).transform_filter(
    interval
)

scatter & hist