Caveat coder: This library is not yet battle-tested.

Video and Slides

Watch the talk on Loom and view slides.

Usage

The namespace loom.graph must be AOT compiled. You can include :aot [loom.graph] in your project.clj to do this. This is due to the issue described on the Clojure mailing list here.

Leiningen/Clojars [group-id/name version]

[brunokim/loom "0.4.1"]

Namespaces

loom.graph - records & constructors
loom.alg   - algorithms (see also loom.alg-generic)
loom.gen   - graph generators
loom.attr  - graph attributes
loom.label - graph labels
loom.io    - read, write, and view graphs in external formats

Basics

Create a graph:

;; Initialize with any of: edges, adacency lists, nodes, other graphs
(def g (graph [1 2] [2 3] {3 [4] 5 [6 7]} 7 8 9))
(def dg (digraph g))
(def wg (weighted-graph {:a {:b 10 :c 20} :c {:d 30} :e {:b 5 :d 5}}))
(def wdg (weighted-digraph [:a :b 10] [:a :c 20] [:c :d 30] [:d :b 10]))
(def rwg (gen-rand (weighted-graph) 10 20 :max-weight 100))
(def fg (fly-graph :successors range :weight (constantly 77)))

If you have GraphViz installed, and its binaries are in the path, you can view graphs with loom.io/view:

(view wdg) ;opens image in default image viewer

Inspect:

(nodes g)
=> #{1 2 3 4 5 6 7 8 9}

(edges wdg)
=> ([:a :c] [:a :b] [:c :d] [:d :b])

(successors g 3)
=> #{2 4}

(predecessors wdg :b)
=> #{:a :d}

(out-degree g 3)
=> 2

(in-degree wdg :b)
=> 2

(weight wg :a :c)
=> 20

(map (juxt graph? directed? weighted?) [g wdg])
=> ([true false false] [true true true])

Add/remove items (graphs are immutable, of course, so these return new graphs):

(add-nodes g "foobar" {:name "baz"} [1 2 3])

(add-edges g [10 11] ["foobar" {:name "baz"}])

(add-edges wg [:e :f 40] [:f :g 50]) ;weighted edges

(remove-nodes g 1 2 3)

(remove-edges g [1 2] [2 3])

(subgraph g [5 6 7])

Traverse a graph:

(bf-traverse g) ;lazy
=> (9 8 5 6 7 1 2 3 4)

(bf-traverse g 1)
=> (1 2 3 4)

(pre-traverse wdg) ;lazy
=> (:a :b :c :d)

(post-traverse wdg) ;not lazy
=> (:b :d :c :a)

(topsort wdg)
=> (:a :c :d :b)

Pathfinding:

(bf-path g 1 4)
=> (1 2 3 4)

(bf-path-bi g 1 4) ;bidirectional, parallel
=> (1 2 3 4)

(dijkstra-path wg :a :d)
=> (:a :b :e :d)

(dijkstra-path-dist wg :a :d)
=> [(:a :b :e :d) 20]

Other stuff:

(connected-components g)
=> [[1 2 3 4] [5 6 7] [8] [9]]

(bf-span wg :a)
=> {:c [:d], :b [:e], :a [:b :c]}

(pre-span wg :a)
=> {:a [:b], :b [:e], :e [:d], :d [:c]}

(dijkstra-span wg :a)
=> {:a {:b 10, :c 20}, :b {:e 15}, :e {:d 20}}

TODO: link to autodocs

Dependencies

Nothing but Clojure. There is optional support for visualization via GrapViz.

TODO

• Use deftype instead of defrecord
• Do more functional graph research
• Solidify basic API, guarantees
• Implement more algorithms
• Test & profile more with big, varied graphs
• Multigraphs, hypergraphs, adjacency matrix-based graphs?

Contributors

Names in no particular order:

• Justin Kramer
• [Aysylu Greenberg] (https://github.com/aysylu), aysylu [dot] greenberg [at] gmail [dot] com, @aysylu22
• Robert Lachlan, robertlachlan@gmail.com
• Stephen Kockentiedt

License

Copyright (C) 2010-2013 Aysylu Greenberg & Justin Kramer (jkkramer@gmail.com)

Distributed under the Eclipse Public License, the same as Clojure.