Scale only one axis in Altair with interactive plot

Question

I am using Altair 4.1.0 to create interactive plots with Python. I want to be able to zoom in some part of my chart by scaling only one axis, for example only the y-axis while keeping the x-axis fixed. From the documentation I could not find a way to do this. My understanding is that alt.interactive() corresponds to .add_selection(alt.selection_interval(bind='scales')) , but still I don't see how to achieve my purpose. Is there any way to do this in Altair?

Answer 1

alt.Chart.interactive has bind_x and bind_y arguments which default to True . If you set either of these to False , that scale will not be part of the interaction:

chart.interactive(bind_x=False)

Alternatively, you can do this manually by specifying the encodings you want bound ( ['x'] , ['y'] , or ['x', 'y'] , which is the default):

chart.add_selection(alt.selection_interval(bind='scales', encodings=['y']))