Type Members

1.  class MonotoneChain extends AnyRef

   Monotone Chains are a way of partitioning the segments of a linestring to allow for fast searching of intersections.

   Monotone Chains are a way of partitioning the segments of a linestring to allow for fast searching of intersections. They have the following properties:

   • the segments within a monotone chain never intersect each other
   • the envelope of any contiguous subset of the segments in a monotone chain is equal to the envelope of the endpoints of the subset.

   Property 1 means that there is no need to test pairs of segments from within the same monotone chain for intersection.

   Property 2 allows an efficient binary search to be used to find the intersection points of two monotone chains. For many types of real-world data, these properties eliminate a large number of segment comparisons, producing substantial speed gains.

   One of the goals of this implementation of MonotoneChains is to be as space and time efficient as possible. One design choice that aids this is that a MonotoneChain is based on a subarray of a list of points. This means that new arrays of points (potentially very large) do not have to be allocated.

   MonotoneChains support the following kinds of queries:

   • Envelope select: determine all the segments in the chain which intersect a given envelope
   • Overlap: determine all the pairs of segments in two chains whose envelopes overlap

   This implementation of MonotoneChains uses the concept of internal iterators ({link MonotoneChainSelectAction} and {link MonotoneChainOverlapAction}) to return the results for queries. This has time and space advantages, since it is not necessary to build lists of instantiated objects to represent the segments returned by the query. Queries made in this manner are thread-safe.

   MonotoneChains support being assigned an integer id value to provide a total ordering for a set of chains. This can be used during some kinds of processing to avoid redundant comparisons (i.e. by comparing only chains where the first id is less than the second).

   Version

   1.7

2.  class MonotoneChainOverlapAction extends AnyRef

   The action for the internal iterator for performing overlap queries on a MonotoneChain

   The action for the internal iterator for performing overlap queries on a MonotoneChain

   Version

   1.7

3.  class MonotoneChainSelectAction extends AnyRef

   The action for the internal iterator for performing envelope select queries on a MonotoneChain

   The action for the internal iterator for performing envelope select queries on a MonotoneChain

   Version

   1.7