Circle

circle mark is similar to point mark, except that (1) the shape value is always set to circle (2) they are filled by default.

Circle Mark Properties

A circle mark definition can contain any standard mark properties and the following special properties:

Click to show table

Property	Type	Description
size	anyOf(number, ExprRef)	Default size for marks. For point/circle/square, this represents the pixel area of the marks. Note that this value sets the area of the symbol; the side lengths will increase with the square root of this value. For bar, this represents the band size of the bar, in pixels. For text, this represents the font size, in pixels. Default value: 30 for point, circle, square marks; width/height’s step 2 for bar marks with discrete dimensions; 5 for bar marks with continuous dimensions; 11 for text marks.

Scatter Plot with Circle

Here is an example scatter plot with circle marks:

import altair as alt
from vega_datasets import data

source = data.cars.url

alt.Chart(source).mark_circle().encode(
   x=("Horsepower:Q"),
   y=("Miles_per_Gallon:Q"),
)