Glossary · Phase 3 · Machine learning
Spatial index
A data structure that finds nearby points or shapes without measuring every one, so location queries stay fast at scale.
[:, None]adds a second axis, turning a row of three numbers into a column, so the subtraction inside the formula pairs every member with every trailhead. For thousands of points this is fast; for millions, real systems use a spatial index, a structure that skips far-away points without measuring them.
Try it now
Most location questions are one of four: how far, what's nearest, which zone, or which way around.
Learn it properly
Location data · Haversine distances, nearest places, GeoJSON, point in polygon and simple maps. About 40 minutes.
Other terms from the same lesson
- GeoJSON: A JSON format for points, lines and polygons on a map, which writes every position as [longitude, latitude].
- great circle: A circle around a sphere's middle, like the equator; the shortest route between two points on Earth runs along one.
- haversine formula: The formula for the great-circle distance between two points on a sphere from their latitudes and longitudes.
- point in polygon: Testing whether a point lies inside a shape, often by counting how many edges a ray from the point crosses: odd means inside.
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