turf.lineSegment

What is turf.lineSegment?

turf.lineSegment takes a LineString, MultiLineString, Polygon, or MultiPolygon and returns a FeatureCollection<LineString> where each feature is a two-vertex segment from the original geometry.

turf.lineSegment(geojson) → FeatureCollection<LineString>

When would you use turf.lineSegment?

Use turf.lineSegment when you need to iterate per-edge — for example, computing bearings per segment, finding the longest or shortest edges, detecting near-colinear edges, or building an r-tree over segments for fast proximity queries.

In Node.js, segment-level operations are the foundation of many custom topology algorithms. Combined with @turf/geojson-rbush, segments give you a performant way to do edge-based spatial queries.

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FAQs

How many segments does a polygon produce?

N − 1 for a closed ring with N coordinates (because the first and last coordinates are duplicates). For polygons with holes, segments from all rings are included.

How do I install just lineSegment?

npm install @turf/line-segment. It depends on @turf/helpers and @turf/meta.

Are the segments ordered?

Yes — they follow the original coordinate sequence, so segment index i connects vertex i to vertex i+1.

Do input properties carry through?

Yes — each segment inherits the parent feature's properties. Overwrite after if you need per-segment attributes.