世界地图投影

此示例显示了世界各国的地图。使用下拉菜单比较地图投影。有关 project 参数的更多详细信息，请参阅 altair.Projection 的 API。

方法语法

import altair as alt
from vega_datasets import data

source = alt.topo_feature(data.world_110m.url, 'countries')

input_dropdown = alt.binding_select(options=[
    "albers",
    "albersUsa",
    "azimuthalEqualArea",
    "azimuthalEquidistant",
    "conicEqualArea",
    "conicEquidistant",
    "equalEarth",
    "equirectangular",
    "gnomonic",
    "mercator",
    "naturalEarth1",
    "orthographic",
    "stereographic",
    "transverseMercator"
], name='Projection ')
param_projection = alt.param(value="equalEarth", bind=input_dropdown)

alt.Chart(source, width=500, height=300).mark_geoshape(
    fill='lightgray',
    stroke='gray'
).project(
    type=alt.expr(param_projection.name)
).add_params(param_projection)

属性语法

import altair as alt
from vega_datasets import data

source = alt.topo_feature(data.world_110m.url, 'countries')

input_dropdown = alt.binding_select(options=[
    "albers",
    "albersUsa",
    "azimuthalEqualArea",
    "azimuthalEquidistant",
    "conicEqualArea",
    "conicEquidistant",
    "equalEarth",
    "equirectangular",
    "gnomonic",
    "mercator",
    "naturalEarth1",
    "orthographic",
    "stereographic",
    "transverseMercator"
], name='Projection ')
param_projection = alt.param(value="equalEarth", bind=input_dropdown)

alt.Chart(source, width=500, height=300).mark_geoshape(
    fill='lightgray',
    stroke='gray'
).project(
    type=alt.expr(param_projection.name)
).add_params(param_projection)
# No channel encoding options are specified in this chart
# so the code is the same as for the method-based syntax.