# this example is from https://altair-viz.github.io/gallery/layered_histogram.html
import pandas as pd
import altair as alt
import numpy as np
np.random.seed(42)
# Generating Data
source = pd.DataFrame({
'Trial A': np.random.normal(0, 0.8, 1000),
'Trial B': np.random.normal(-2, 1, 1000),
'Trial C': np.random.normal(3, 2, 1000)
})
alt.Chart(source).transform_fold(
['Trial A', 'Trial B', 'Trial C'],
as_=['Experiment', 'Measurement']
).mark_bar(
opacity=0.3,
binSpacing=0
).encode(
alt.X('Measurement:Q').bin(maxbins=100),
alt.Y('count()').stack(None),
alt.Color('Experiment:N')
)