Grouped Bar Chart with xOffset and overlapping bars

Like Grouped Bar Chart with xOffset, this example shows a grouped bar chart using the xOffset encoding channel, but in this example the bars are partly overlapping within each group.

Method syntax

import altair as alt
import pandas as pd

source = pd.DataFrame(
    {
        "category": list("AABBCC"),
        "group": list("xyxyxy"),
        "value": [0.1, 0.6, 0.7, 0.2, 0.6, 0.1],
    }
)

base = alt.Chart(source, width=alt.Step(12)).encode(
    x="category:N",
    y="value:Q",
    xOffset=alt.XOffset("group:N").scale(paddingOuter=0.5),
)

alt.layer(
    base.mark_bar(size=20, stroke="white", fillOpacity=0.9).encode(fill="group:N"),
    base.mark_text(dy=-5).encode(text="value:Q"),
)

Attribute syntax

import altair as alt
import pandas as pd

source = pd.DataFrame(
    {
        "category": list("AABBCC"),
        "group": list("xyxyxy"),
        "value": [0.1, 0.6, 0.7, 0.2, 0.6, 0.1],
    }
)

base = alt.Chart(source, width=alt.Step(12)).encode(
    x="category:N",
    y="value:Q",
    xOffset=alt.XOffset("group:N", scale=alt.Scale(paddingOuter=0.5)),
)

alt.layer(
    base.mark_bar(size=20, stroke="white", fillOpacity=0.9).encode(fill="group:N"),
    base.mark_text(dy=-5).encode(text="value:Q"),
)