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Article contents:[[tags:egg]] == digraph Directed graph in adjacency list format. [[toc:]] == Documentation The {{digraph}} library is an implementation of a directed graph, where the edges are stored as adjacency lists indexed by node number. The present version implements a [[yasos|yasos object]] that provides a number of methods for graph operations. === Directed graph procedures The digraph object is created by procedure {{make-digraph}}: <procedure>make-digraph:: NAME INFO [NODE-LIST [SUCC-LIST [PRED-LIST]]] -> SELECTOR</procedure> where: * {{NAME}} is the graph name (string or symbol) * {{INFO}} is an optional metadata object of an arbitrary type or {{#f}} * {{NODE-LIST}} is an optional list of nodes to be inserted in the graph; each element of the list must be of the form {{(N INFO)}} where {{N}} is a unique node number (integer), and {{INFO}} is an optional metadata object describing the node. * {{SUCC-LIST}} and {{PRED-LIST}} can be used to define the graph edges upon graph creation. If supplied, these arguments must be lists in which every element is of the form {{(I J INFO)}}, where {{I}} and {{J}} are node numbers, and {{INFO}} is an optional metadata object. The returned [[yasos]] object supports the following operations: ; {{name}} : returns the graph name (string or symbol) ; {{info}} : returns the graph metadata (arbitrary type) ; {{new-id!}} : returns a procedure with no arguments, which returns the lowest available node number ; {{add-node!}} : procedure {{LAMBDA N INFO}} which inserts in the graph node with number {{N}} and metadata {{INFO}}; if the node already exists in the graph, it will be overwritten with the new metadata ; {{add-edge!}} : procedure {{LAMBDA EDGE}} which inserts in the graph the specifed edge; the edge is given by a list of the form {{(I J INFO)}}, where {{I}} and {{J}} are source and destination nodes, respectively, and {{INFO}} is edge metadata of arbitrary type ; {{remove-node!}} : procedure {{LAMBDA N}} which removes node {{N}} and all its edges from the graph ; {{nodes}} : returns a list with the nodes of the graph and their metadata ; {{edges}} : returns a list with the edges of the graph and their metadata ; {{roots}} : returns a list with all nodes in the graph that do not have an predecessor ; {{terminals}} : which returns a list with all nodes in the graph that do not have a successor ; {{order}} : returns the number of nodes in the graph ; {{size}} : returns the number of edges in the graph ; {{capacity}} : returns the size of the underlying dynamic vector ; {{succ}} : procedure {{LAMBDA N}} which returns a list with the successor nodes of node {{N}} ; {{pred}} : procedure {{LAMBDA N}} which returns a list with the predecessor nodes of node {{N}} ; {{succ-list}} : returns a list containing the successor nodes for each node. ; {{pred-list}} : returns a list containing the predecessor nodes for each node. ; {{out-edges}} : procedure {{LAMBDA N}} which returns a list with the outgoing edges of node {{N}} ; {{in-edges}} : procedure {{LAMBDA N}} which returns a list with the incoming edges of node {{N}} ; {{has-edge}} : procedure {{LAMBDA I J}} which returns true if edge {{I -> J}} exists in the graph and false otherwise ; {{has-node}} : procedure {{LAMBDA N}} which returns true if node {{N}} exists in the graph and false otherwise ; {{node-info}} : procedure {{LAMBDA N}} which returns the metadata for node {{N}} ; {{node-info-set!}} : procedure {{LAMBDA N V}} which sets the metadata for node {{N}} ; {{foreach-node}} : procedure {{LAMBDA F}} which iterates over the nodes in the graph by invoking function {{F}} on the node number and metadata of each node ; {{foreach-edge}} : procedure {{LAMBDA F}} which iterates over the edges in the graph by invoking function {{F}} on each edge == Examples ;; example adapted from graph example in the Boost library documentation (import srfi-1 digraph matchable) (define g (make-digraph 'depgraph "dependency graph")) (define used-by (list (cons 'dax_h 'foo_cpp) (cons 'dax_h 'bar_cpp) (cons 'dax_h 'yow_h) (cons 'yow_h 'bar_cpp) (cons 'yow_h 'zag_cpp) (cons 'boz_h 'bar_cpp) (cons 'boz_h 'zig_cpp) (cons 'boz_h 'zag_cpp) (cons 'zow_h 'foo_cpp) (cons 'foo_cpp 'foo_o) (cons 'foo_o 'libfoobar_a) (cons 'bar_cpp 'bar_o) (cons 'bar_o 'libfoobar_a) (cons 'libfoobar_a 'libzigzag_a) (cons 'zig_cpp 'zig_o) (cons 'zig_o 'libzigzag_a) (cons 'zag_cpp 'zag_o) (cons 'zag_o 'libzigzag_a) (cons 'libzigzag_a 'killerapp))) (define node-list (delete-duplicates (concatenate (list (map car used-by) (map cdr used-by))))) (define node-ids (list-tabulate (length node-list) values)) (for-each (lambda (i n) (add-node! g i n)) node-ids node-list) (define node-map (zip node-list node-ids)) (for-each (lambda (e) (match e ((ni . nj) (let ((i (car (alist-ref ni node-map))) (j (car (alist-ref nj node-map)))) (add-edge! g (list i j (format "~A->~A" ni nj))))) (else (error "invalid edge " e)))) used-by) (print (nodes g)) (print (edges g)) (remove-node! g 0) (print (nodes g)) (print (edges g)) == About this egg === Author [[/users/ivan-raikov|Ivan Raikov]] === Repository [[https://github.com/iraikov/chicken-digraph|https://github.com/iraikov/chicken-digraph]] === Version history ; 2.0 : Ported to CHICKEN 5 and yasos ; 1.16 : Added terminals message to digraph object ; 1.15 : Ensure unit test script return proper exit code ; 1.13 : Added test as a test dependency ; 1.12 : Converted documentation to wiki format ; 1.11 : Ported to Chicken 4 ; 1.10 : Now using matchable extension ; 1.9 : Added procedures pred-list and succ-list ; 1.8 : Added procedure node-info-set! ; 1.7 : Build script updated for better cross-platform compatibility ; 1.6 : Test infrastructure changed to use testbase ; 1.5 : Bug fixes in set-out-edges! and set-in-edges! [thanks to Andreas Scholta] ; 1.4 : License upgrade to GPL v3 ; 1.3 : Updated the roots procedure to match the documentation ; 1.2 : Minor changes to the setup script ; 1.1 : Added support for chicken-setup -test ; 1.0 : Initial release === License Copyright 2007-2018 Ivan Raikov. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. A full copy of the GPL license can be found at <http://www.gnu.org/licenses/>. Description of your changes:

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