我正在尝试用色阶图对百分比进行编码。如何设置比例尺以显示百分比值(例如 10%),而不是分数值(例如 0.1)?我知道对于常规的 X 或 Y 轴,您可以使用 axis=alt.Axis(format='.0%')
进行格式化,但我不知道如何为此颜色比例尺使用格式化。
import altair as alt
import pandas as pd
from vega_datasets import data
alt.renderers.enable('notebook')
airports = pd.read_csv(data.airports.url)
airports = airports.groupby('state').agg({'iata': 'count'})
airports['id'] = range(1, len(airports) + 1)
airports['pct'] = airports['iata'] / airports['iata'].sum()
states = alt.topo_feature(data.us_10m.url, feature='states')
alt.Chart(states).mark_geoshape().encode(
color='pct:Q'
).transform_lookup(
lookup='id',
from_=alt.LookupData(airports, 'id', ['pct'])
).project('albersUsa')