Repeated Density Estimates

Density estimates for each feature of iris flower. This is what we call a “repeated” plot, with one subplot for each feature.

Method syntax

import altair as alt
from vega_datasets import data

source = data.iris()

alt.Chart(source).transform_fold(
    [
        "petalWidth",
        "petalLength",
        "sepalWidth",
        "sepalLength",
    ],
    as_=["Measurement_type", "value"],
).transform_density(
    density="value",
    bandwidth=0.3,
    groupby=["Measurement_type"],
    extent=[0, 8],
).mark_area().encode(
    alt.X("value:Q"),
    alt.Y("density:Q"),
    alt.Row("Measurement_type:N"),
).properties(
    width=300, height=50
)

Attribute syntax

import altair as alt
from vega_datasets import data

source = data.iris()

alt.Chart(source).transform_fold(
    [
        "petalWidth",
        "petalLength",
        "sepalWidth",
        "sepalLength",
    ],
    as_=["Measurement_type", "value"],
).transform_density(
    density="value",
    bandwidth=0.3,
    groupby=["Measurement_type"],
    extent=[0, 8],
).mark_area().encode(
    alt.X("value:Q"),
    alt.Y("density:Q"),
    alt.Row("Measurement_type:N"),
).properties(
    width=300, height=50
)
# No channel encoding options are specified in this chart
# so the code is the same as for the method-based syntax.