Algorithmic Solutions > LEDA > LEDA Guide > Graphs and Related Data Types > Planar Maps
Planar MapsIt is often useful to visualize the relations represented by a graph to understand them better or to discover new properties. To visualize the relations we need to draw graphs. The nodes are usually drawn as circles or boxes and the edges as lines connecting the nodes.
The data type planar_map represents a planar drawing of a planar graph. A graph is called planar if it can be drawn without edge crossings.
A Planar Map is a bidirected graph and for every node v the cyclic ordering of the edges out of v corresponds to the ordering of the edges around v in the drawing. Nodes and edges are of type item.
A crossing-free drawing of graph in the plane partitions the plane into connected regions, called faces of the drawing. We can associate information with the faces of a Planar Map using Face Arrays and Face Maps .
Remark: Originally, only the data type
Use Planar Maps if you want to ensure that all operations performed
on your planar map result in a planar map. Otherwise use
Remark: Our experience shows that we rarely use the data type
GraphWin for visualizing graphs and graph algorithms
How to Associate Information with nodes and edges