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+%22%22%22%0ALayered chart with Dual-Axis%0A----------------------------%0AThis example shows how to create a second independent y axis.%0A%22%22%22%0A# category: other charts%0A%0Aimport altair as alt%0Afrom vega_datasets import data%0A%0Asource = data.seattle_weather()%0A%0Abase = alt.Chart(source).encode(%0A    alt.X('month(date):T', axis=alt.Axis(title=None))%0A)%0A%0Aarea = base.mark_area(opacity=0.3, color='#57A44C').encode(%0A    alt.Y('average(temp_max)',%0A          axis=alt.Axis(title='Avg. Temperature (%C2%B0C)', titleColor='#57A44C')),%0A    alt.Y2('average(temp_min)')%0A)%0A%0Aline = base.mark_line(stroke='#5276A7', interpolate='monotone').encode(%0A    alt.Y('average(precipitation)',%0A          axis=alt.Axis(title='Precipitation (inches)', titleColor='#5276A7'))%0A)%0A%0Aalt.layer(area, line).resolve_scale(%0A    y = 'independent'%0A)%0A

add dual y axis example