步骤图

此示例显示了谷歌的股票价格随时间的变化。 这使用了“step-after”插值方案。 插值选项的完整列表包括‘linear’， ‘linear-closed’，‘step’，‘step-before’，‘step-after’，‘basis’， ‘basis-open’，‘basis-closed’，‘cardinal’，‘cardinal-open’， ‘cardinal-closed’，‘bundle’，和‘monotone’。

Method syntax

import altair as alt
from vega_datasets import data

source = data.stocks()

alt.Chart(source).mark_line(interpolate='step-after').encode(
    x='date',
    y='price'
).transform_filter(
    alt.datum.symbol == 'GOOG'
)

Attribute syntax

import altair as alt
from vega_datasets import data

source = data.stocks()

alt.Chart(source).mark_line(interpolate='step-after').encode(
    x='date',
    y='price'
).transform_filter(
    alt.datum.symbol == 'GOOG'
)
# No channel encoding options are specified in this chart
# so the code is the same as for the method-based syntax.