Path Finding: A* or Dijkstra's?
PATH FINDING: A* OR DIJKSTRA’S?
Abstract
It is well known that computing shortest paths over a network is an important task in many network and transportation related analyses. Choosing an adequate algorithm from the numerous algorithms reported in the literature is a critical step in many applications involving real road networks. In a recent study, a set of two shortest path algorithms that run fastest on real road networks has been identified. These two algorithms are: 1) the A* algorithm, 2) the Dijkstra’s algorithm. As a sequel to that study, this paper reviews and summarizes these two algorithms, and demonstrates the data structures and procedures related to the algorithms.
Keywords - A* algorithm, Dijkstra’s Algorithm, Heuristic Function, Geographic
Information System, Transportation.
Introduction
With the development of geographic information systems (GIS) technology, network and transportation analyses within a GIS environment have become a common practice in many application areas. A key problem in network and transportation analyses is the computation of shortest paths between different locations on a network. Sometimes this computation has to be done in real time. For the sake of
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illustration, let us have a look at a situation in which a place has been hit with natural disaster. Now many persons may got stuck at different places but they have to be rescued anyhow. So, the main problem that rescue team face is that how they(rescuer) approach them i.e. which path they should opt from numerous available paths. Hence, the fastest route can only be determined in real time. In some cases the fastest route has to be determined in a few seconds in order to ensure the safety of a stuck people. Moreover, when large real road networks are involved in an application, the determination of shortest paths on a large network can be computationally very intensive. Because many applications involve real road networks and because
Abstract
It is well known that computing shortest paths over a network is an important task in many network and transportation related analyses. Choosing an adequate algorithm from the numerous algorithms reported in the literature is a critical step in many applications involving real road networks. In a recent study, a set of two shortest path algorithms that run fastest on real road networks has been identified. These two algorithms are: 1) the A* algorithm, 2) the Dijkstra’s algorithm. As a sequel to that study, this paper reviews and summarizes these two algorithms, and demonstrates the data structures and procedures related to the algorithms.
Keywords - A* algorithm, Dijkstra’s Algorithm, Heuristic Function, Geographic
Information System, Transportation.
Introduction
With the development of geographic information systems (GIS) technology, network and transportation analyses within a GIS environment have become a common practice in many application areas. A key problem in network and transportation analyses is the computation of shortest paths between different locations on a network. Sometimes this computation has to be done in real time. For the sake of
-1-
illustration, let us have a look at a situation in which a place has been hit with natural disaster. Now many persons may got stuck at different places but they have to be rescued anyhow. So, the main problem that rescue team face is that how they(rescuer) approach them i.e. which path they should opt from numerous available paths. Hence, the fastest route can only be determined in real time. In some cases the fastest route has to be determined in a few seconds in order to ensure the safety of a stuck people. Moreover, when large real road networks are involved in an application, the determination of shortest paths on a large network can be computationally very intensive. Because many applications involve real road networks and because
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