Binned Heatmap
This example shows how to make a heatmap from binned quantitative data.
import altair as alt
from vega_datasets import data
source = data.movies.url
alt.Chart(source).mark_rect().encode(
alt.X('IMDB_Rating:Q', bin=alt.Bin(maxbins=60)),
alt.Y('Rotten_Tomatoes_Rating:Q', bin=alt.Bin(maxbins=40)),
alt.Color('count():Q', scale=alt.Scale(scheme='greenblue'))
)