Set a diverging color scheme to center on zero in Altair

Question

How can I go about getting the colour scale to center on zero for a diverging colour scale.

Answer 1

We can now use domainMid=0.

Adapting the example from @jakevdp:

df = pd.DataFrame(np.random.randn(100, 3), columns=['x', 'y', 'z'])
alt.Chart(df).mark_point().encode(
    x='x',
    y='y',
    color=alt.Color('z', scale=alt.Scale(scheme='blueorange', domainMid=0))
)