交互式矩形刷#
本示例展示了如何向散点图添加一个简单的矩形刷。通过在图表上单击并拖动,您可以突出显示范围内的点。
import altair as alt
from vega_datasets import data
source = data.cars()
brush = alt.selection_interval()
alt.Chart(source).mark_point().encode(
x='Horsepower:Q',
y='Miles_per_Gallon:Q',
color=alt.when(brush).then("Cylinders:O").otherwise(alt.value("grey")),
).add_params(brush)
import altair as alt
from vega_datasets import data
source = data.cars()
brush = alt.selection_interval()
alt.Chart(source).mark_point().encode(
x='Horsepower:Q',
y='Miles_per_Gallon:Q',
color=alt.when(brush).then("Cylinders:O").otherwise(alt.value("grey")),
).add_params(brush)
# No channel encoding options are specified in this chart
# so the code is the same as for the method-based syntax.