World Projections

This example shows a map of the countries of the world. Use the dropdown menu to compare projections. For more details on the project arguments, see the API of altair.Projection.

Method syntax

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)

Attribute syntax

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.