"""
World Projections
-----------------
This example shows a map of the countries of the world using four available
geographic projections. For more details on the projections available in
Altair, see https://vega.github.io/vega-lite/docs/projection.html
"""
# category: maps
import altair as alt
from vega_datasets import data

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

base = alt.Chart(source).mark_geoshape(
    fill='#666666',
    stroke='white'
).properties(
    width=300,
    height=180
)

projections = ['equirectangular', 'mercator', 'orthographic', 'gnomonic']
charts = [base.project(proj).properties(title=proj)
          for proj in projections]

alt.concat(*charts, columns=2)