Two-Dimensional Node Maps ( node_map2 )

Definition

An instance of the data type node_map2<E> is a map2 for the pairs of nodes of a graph G, i.e., equivalent to map2 < node, node, E > (cf. Two-Dimensional Maps). It can be used as a dynamic variant of the data type node$\_$matrix(cf. Two Dimensional Node Arrays).

#include < LEDA/node_map2.h >

Creation

node_map2<E>	M	introduces a variable M of type node_map2<E> and initializes it to the map2 with empty domain.
node_map2<E>	M(graph_t G)	introduces a variable M of type node_map2<E> and initializes it with a mapping m from the set of all nodes of G into the set of variables of type E. The variables in the range of m are initialized by a call of the default constructor of type E.
node_map2<E>	M(graph_t G, E x)	introduces a variable M of type node_map2<E> and initializes it with a mapping m from the set of all nodes of G into the set of variables of type E. The variables in the range of m are initialized with a copy of x.

Operations

void	M.init()	makes M a node map2 with empty domain.
void	M.init(graph_t G)	makes M to a mapping m from the set of all nodes of G into the set of variables of type E. The variables in the range of m are initialized by a call of the default constructor of type E.
void	M.init(graph_t G, E x)	makes M to a mapping m from the set of all nodes of G into the set of variables of type E. The variables in the range of m are initialized with a copy of x.
E&	M(node v, node w)	returns the variable M(v, w).
bool	M.defined(node v, node w)	returns true if (v, w) $\in$ dom(m) and false otherwise.

Implementation

Node maps are implemented by an efficient hashing method based on the internal numbering of the nodes. An access operation takes expected time O(1).