在altair图表python中显示B(十亿)而不是G(Giga

import altair as alt
import pandas as pd

data = pd.DataFrame({'Category': ['A', 'B', 'C'],
                     'Value': [1000000000, 2000000000, 3000000000]})

chart = alt.Chart(data).mark_bar().encode(
    x='Category',
    y=alt.Y('Value', axis=alt.Axis(format='.1s', labelFlush=False))
)

chart.show()