How to remove border box on arc charts when saving to png

[mcp292]

MWE

import pandas as pd
import altair as alt


source = pd.DataFrame({"category": [1, 2, 3, 4, 5, 6], "value": [4, 6, 10, 3, 7, 8]})

alt.Chart(source).mark_arc(stroke="black").encode(
    theta=alt.Theta(field="value", type="quantitative"),
    color=alt.Color(field="category", type="nominal"),
).save("arc.png", webdriver="firefox")

Question

Is there a way to get rid of the border box? It seems to be related to saving to png as the example linked above does not have it. It is present with and without stroke.

[joelostblom]

This section of the docs shows that https://altair-viz.github.io/user_guide/customization.html#removing-the-chart-border. Actually maybe we should update that to use stroke=None which might be more semantacally pleasing (but same effect as strokeWith=0.

[mcp292]

I'm happy to see this in the docs! Thanks for the link!

Is the default for HTML plots strokeWidth=0 then?

I think you mean strokeWidth=None, in which case I do like that too.

[joelostblom]

stroke=None seems to work for me. And I see the outline in html as well unless I include that line.

[mcp292]

Oh, yes you're correct, my mistake:

alt.Chart(source).mark_arc(stroke="black").encode(
    theta=alt.Theta(field="value", type="quantitative"),
    color=alt.Color(field="category", type="nominal")
).configure_view(
    stroke=None
).save("arc.png", webdriver="firefox")