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# astar

Pathfinding using A* algorithm

## Releases and Dependency Information

Latest release is [0.2]

Leiningen dependency information:

```
[astar-search "0.2"]
```

Maven dependency information:

```
<dependency>
<groupId>astar-search</groupId>
<artifactId>astar-search</artifactId>
<version>0.1.1</version>
</dependency>
```

## Usage

`astar.core/route`

takes the following parameters:

`graph`

, which is a function (eg. a map) from a node to all neighbors of that node.

```
user=> (def graph {:a [:b :c]
:b [:a :d :e]
:c [:a :d :e]
:d [:b :c :f]
:e [:b :c :f]
:f [:e :d]})
#'user/graph
```

`dist`

, which is a function from two nodes to the distance (as a number) from the first node to the second.

```
user=> (defn dist [from to]
(let [d {:a {:b 4 :c 2}
:b {:a 4 :d 1 :e 1}
:c {:a 2 :d 3 :e 5}
:d {:b 1 :c 3 :f 3}
:e {:b 1 :c 5 :f 2}
:f {:d 3 :e 2}}]
(get-in d [from to])))
#'user/dist
```

`h`

, which is a function from a node to the heuristic distance from that node to the goal. It should never overestimate the distance. If it does, the algorithm isn’t guaranteed to find the optimal solution.

```
user=> (def h {:a 7
:b 3
:c 6
:d 3
:e 2
:f 0})
#'user/h
```

`start`

, which is the starting node for the search`goal`

, which is the goal node for the search.

It returns a list of nodes that form the shortest path from the start node (exclusive) to the goal node (inclusive).

```
user=> (require 'astar.core)
nil
user=> (astar.core/route graph dist h :a :f)
(:b :e :f)
```

If a route doesn’t exist, it returns `nil`

.