Version 5.0 The LEDA User Manual

Chapter 15
Advanced Data Types for
Two-Dimensional Geometry
15.1 Two-Dimensional Dictionaries ( d2 dictionary )
1. Definition
An instance D of the parameterized data type d2 dictionary is a collection
of items (dic2 item). Every item in D contains a key from the linearly ordered data type
K1, a key from the linearly ordered data type K2, and an information from data type I.
K1 and K2 are called the key types of D, and I is called the information type of D. If K1
resp. K2 are user-defined types, you have to provide a compare function for type K1 resp.
K2 (see Section 2.3). The number of items in D is called the size of D. A two-dimensional
dictionary of size zero is said to be empty. We use to denote the item with
first key k 1 , second key k 2 , and information i. For each pair (k 1 , k 2 ) ∈ K1 × K2 there is
at most one item ∈ D. Additionally to the normal dictionary operations, the
data type d2 dictionary supports rectangular range queries on K1 × K2.
#include < LEDA/geo/d2 dictionary.h >
2. Creation
d2 dictionary D;
creates an instance D of type d2 dictionary and initializes
D to the empty dictionary.
3. Operations
const K1 & D.key1(dic2 item it) returns the first key of item it.
Precondition: it is an item in D.
const K2 & D.key2(dic2 item it) returns the second key of item it.
Precondition: it is an item in D.
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