Range searching

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Simplex range searching.

In its most general form, the range searching problem consists of preprocessing a set S of objects, in order to determine which objects from S intersect with a query object, called a range. For example, S may be a set of points corresponding to the coordinates of several cities, and we want to find the cities within a certain latitude and longitude range.

The range searching problems and data structures are a fundamental topic of computational geometry. The range searching problem finds applications not only in areas that deal with processing geometrical data (like geographical information systems (GIS), and CAD), but also in databases.

Variations[edit]

There are several variations of the problem, and different data structures may be necessary for different variations. In order to obtain an efficient solution, several aspects of the problem need to be specified:

  • Query types: If the list of all objects that intersect the query range must be reported, the problem is called range reporting, and the query is called a reporting query. Sometimes, only the number of objects that intersect the range is required. In this case, the problem is called range counting, and the query is called a counting query. The emptiness query reports whether there is at least one object that intersects the range. In the semigroup version, a commutative semigroup (S,+) is specified, each point is assigned a weight from S, and it is required to report the semigroup sum of the weights of the points that intersect the range.
  • Dynamic range searching vs. static range searching: In the static setting the set S is known in advance. In dynamic setting objects may be inserted or deleted between queries.

See also[edit]

Range Minimum Query

References[edit]