Filtering and bounds

The two GeoMap panels share bounds={[4, 44, 25, 56]}. The first draws the whole source; the second uses world_countries({ ids }) to keep Germany, Poland, Czechia, Austria, and Switzerland. Their scale and placement agree because bounds fitting does not depend on source geometry.

ids filters features before borders are built. It keeps the shared TopoJSON arc table, so internal borders still work. The same option is available on us_states, geojson, and topojson. Preserve leading zeros in string IDs.

Bounds mean [west, south, east, north] in degrees. They fit the region and clip all map content to its projected outline, preserving the projection's proportions and leaving unused allocation transparent. Within the bounds, the water background also shows wherever countries have been omitted. Bounds override fit-to; omit them to use fit-to="data" for the selected countries themselves, or fit-to={ids} to fit a subset while still drawing the full source.

Both panels nest the same geographic Polyline and Points for a Berlin–Prague–Vienna route. Each map supplies its projection to those children. See Making maps for the full workflow.

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Filtering and bounds

Filtering and bounds