Simple Scatter Plot with Tooltips
A scatter plot of the cars dataset, with tooltips showing selected column values when you hover over points. We make the points larger so that it is easier to hover over them.
import altair as alt
from vega_datasets import data
source = data.cars()
alt.Chart(source).mark_circle(size=60).encode(
x='Horsepower',
y='Miles_per_Gallon',
color='Origin',
tooltip=['Name', 'Origin', 'Horsepower', 'Miles_per_Gallon']
).interactive()