Grouped bar chart in newer versions of altair (>= 4.2.0)

Question

I am trying to create a grouped bar chart in altair like in the answer to this question here.

The particular interesting part is the "beautification:

chart = Chart(df).mark_bar().encode(
   column=Column('Genre', 
                 axis=Axis(axisWidth=1.0, offset=-8.0, orient='bottom'),
                 scale=Scale(padding=4.0)),
   x=X('Gender', axis=False),
   y=Y('Rating', axis=Axis(grid=False)),
   color=Color('Gender', scale=Scale(range=['#EA98D2', '#659CCA']))
).configure_facet_cell(
    strokeWidth=0.0,
)

chart.display()

The issue is, however, that none of the stuff in the columns (alt.Column) works in the current version of Altair (I am using 4.2).

In particular, I am getting:

SchemaValidationError: Invalid specification altair.vegalite.v4.schema.channels.Column, validating 'additionalProperties' Additional properties are not allowed ('axis' was unexpected)

Can something similar still be done?

Answer 1

In Altair 4.2.0 you achieve a similar results like this (not sure if you can connect the facets with the x-axis line):

import altair as alt
import pandas as pd

# create dataframe
df = pd.DataFrame([['Action', 5, 'F'], 
                   ['Crime', 10, 'F'], 
                   ['Action', 3, 'M'], 
                   ['Crime', 9, 'M']], 
                  columns=['Genre', 'Rating', 'Gender'])

chart = alt.Chart(df).mark_bar().encode(
   column=alt.Column(
       'Genre', 
       header=alt.Header(orient='bottom')
    ),
   x=alt.X('Gender', axis=alt.Axis(ticks=False, labels=False, title='')),
   y=alt.Y('Rating', axis=alt.Axis(grid=False)),
   color='Gender'
).configure_view(
    stroke=None,
)

chart

In the current development version of Altair (will probably be released as 5.0), you can use the new offset channels to achieve the same result without faceting:

chart = alt.Chart(df).mark_bar().encode(
   x=alt.X('Genre', axis=alt.Axis(labelAngle=0)),
   xOffset='Gender',
   y=alt.Y('Rating', axis=alt.Axis(grid=False)),
   color='Gender'
).configure_view(
    stroke=None,
)

chart