Dynamically determine aggregate KeyBounds in GeoTrellis

Question

Given an RDD[(SpatialKey, Tile)] in GeoTrellis, how do I compute the aggregate KeyBounds[SpatialKey]?

Answer 1

For any RDD[(K, V])] where K is Boundable, i.e. there is an implicit Boundable[K] in scope, you can do:

val bounds: KeyBounds[K] =
  tiles.map({ case (key, _) => KeyBounds(key, key) }).reduce(_ combine _)

This will work over SpatialKey and SpaceTimeKey, as GeoTrellis provides the implicit Boundable typeclasses for those types. So in your case,

val bounds: KeyBounds[SpatialKey] =
  tiles.map({ case (key, _) => KeyBounds(key, key) }).reduce(_ combine _)

will work.