Cumulative Count Chart
This example shows an area chart with cumulative count. Adapted from https://vega.github.io/vega-lite/examples/area_cumulative_freq.html
import altair as alt
from vega_datasets import data
source = data.movies.url
alt.Chart(source).transform_window(
cumulative_count="count()",
sort=[{"field": "IMDB_Rating"}],
).mark_area().encode(
x="IMDB_Rating:Q",
y="cumulative_count:Q"
)