1 | [[tags:egg]] |
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2 | |
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3 | == digraph |
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4 | |
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5 | Directed graph in adjacency list format. |
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6 | |
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7 | [[toc:]] |
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8 | |
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9 | == Documentation |
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10 | |
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11 | |
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12 | The {{digraph}} library is an implementation of a directed graph, where |
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13 | the edges are stored as adjacency lists indexed by node number. |
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14 | |
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15 | The present version implements a [[yasos|yasos object]] |
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16 | that provides a number of methods for graph operations. |
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17 | |
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18 | === Directed graph procedures |
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19 | |
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20 | |
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21 | The digraph object is created by procedure {{make-digraph}}: |
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22 | |
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23 | <procedure>make-digraph:: NAME INFO [NODE-LIST [SUCC-LIST [PRED-LIST]]] -> SELECTOR</procedure> |
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24 | |
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25 | where: |
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26 | |
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27 | * {{NAME}} is the graph name (string or symbol) |
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28 | * {{INFO}} is an optional metadata object of an arbitrary type or {{#f}} |
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29 | * {{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. |
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30 | * {{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. |
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31 | |
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32 | |
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33 | The returned [[yasos]] object supports the following operations: |
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34 | |
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35 | ; {{name}} : returns the graph name (string or symbol) |
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36 | ; {{info}} : returns the graph metadata (arbitrary type) |
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37 | ; {{new-id!}} : returns a procedure with no arguments, which returns the lowest available node number |
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38 | ; {{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 |
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39 | ; {{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 |
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40 | ; {{remove-node!}} : procedure {{LAMBDA N}} which removes node {{N}} and all its edges from the graph |
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41 | ; {{nodes}} : returns a list with the nodes of the graph and their metadata |
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42 | ; {{edges}} : returns a list with the edges of the graph and their metadata |
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43 | ; {{roots}} : returns a list with all nodes in the graph that do not have an predecessor |
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44 | ; {{terminals}} : which returns a list with all nodes in the graph that do not have a successor |
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45 | ; {{order}} : returns the number of nodes in the graph |
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46 | ; {{size}} : returns the number of edges in the graph |
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47 | ; {{capacity}} : returns the size of the underlying dynamic vector |
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48 | ; {{succ}} : procedure {{LAMBDA N}} which returns a list with the successor nodes of node {{N}} |
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49 | ; {{pred}} : procedure {{LAMBDA N}} which returns a list with the predecessor nodes of node {{N}} |
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50 | ; {{succ-list}} : returns a list containing the successor nodes for each node. |
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51 | ; {{pred-list}} : returns a list containing the predecessor nodes for each node. |
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52 | ; {{out-edges}} : procedure {{LAMBDA N}} which returns a list with the outgoing edges of node {{N}} |
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53 | ; {{in-edges}} : procedure {{LAMBDA N}} which returns a list with the incoming edges of node {{N}} |
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54 | ; {{has-edge}} : procedure {{LAMBDA I J}} which returns true if edge {{I -> J}} exists in the graph and false otherwise |
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55 | ; {{has-node}} : procedure {{LAMBDA N}} which returns true if node {{N}} exists in the graph and false otherwise |
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56 | ; {{node-info}} : procedure {{LAMBDA N}} which returns the metadata for node {{N}} |
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57 | ; {{node-info-set!}} : procedure {{LAMBDA N V}} which sets the metadata for node {{N}} |
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58 | ; {{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 |
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59 | ; {{foreach-edge}} : procedure {{LAMBDA F}} which iterates over the edges in the graph by invoking function {{F}} on each edge |
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60 | |
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61 | |
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62 | == Examples |
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63 | |
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64 | ;; example adapted from graph example in the Boost library documentation |
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65 | (import srfi-1 digraph matchable) |
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66 | |
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67 | (define g (make-digraph 'depgraph "dependency graph")) |
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68 | |
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69 | (define used-by |
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70 | (list |
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71 | (cons 'dax_h 'foo_cpp) (cons 'dax_h 'bar_cpp) (cons 'dax_h 'yow_h) |
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72 | (cons 'yow_h 'bar_cpp) (cons 'yow_h 'zag_cpp) (cons 'boz_h 'bar_cpp) |
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73 | (cons 'boz_h 'zig_cpp) (cons 'boz_h 'zag_cpp) (cons 'zow_h 'foo_cpp) |
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74 | (cons 'foo_cpp 'foo_o) (cons 'foo_o 'libfoobar_a) |
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75 | (cons 'bar_cpp 'bar_o) (cons 'bar_o 'libfoobar_a) |
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76 | (cons 'libfoobar_a 'libzigzag_a) (cons 'zig_cpp 'zig_o) |
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77 | (cons 'zig_o 'libzigzag_a) (cons 'zag_cpp 'zag_o) |
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78 | (cons 'zag_o 'libzigzag_a) (cons 'libzigzag_a 'killerapp))) |
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79 | |
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80 | |
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81 | (define node-list (delete-duplicates |
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82 | (concatenate (list (map car used-by) (map cdr used-by))))) |
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83 | |
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84 | (define node-ids (list-tabulate (length node-list) values)) |
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85 | |
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86 | (for-each (lambda (i n) (add-node! g i n)) node-ids node-list) |
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87 | (define node-map (zip node-list node-ids)) |
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88 | |
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89 | (for-each (lambda (e) |
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90 | (match e ((ni . nj) (let ((i (car (alist-ref ni node-map))) |
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91 | (j (car (alist-ref nj node-map)))) |
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92 | (add-edge! g (list i j (format "~A->~A" ni nj))))) |
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93 | (else (error "invalid edge " e)))) |
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94 | used-by) |
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95 | (print (nodes g)) |
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96 | (print (edges g)) |
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97 | |
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98 | (remove-node! g 0) |
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99 | (print (nodes g)) |
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100 | (print (edges g)) |
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101 | |
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102 | == About this egg |
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103 | |
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104 | |
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105 | === Author |
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106 | |
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107 | [[/users/ivan-raikov|Ivan Raikov]] |
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108 | |
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109 | === Version history |
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110 | |
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111 | ; 2.0 : Ported to CHICKEN 5 and yasos |
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112 | ; 1.16 : Added terminals message to digraph object |
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113 | ; 1.15 : Ensure unit test script return proper exit code |
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114 | ; 1.13 : Added test as a test dependency |
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115 | ; 1.12 : Converted documentation to wiki format |
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116 | ; 1.11 : Ported to Chicken 4 |
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117 | ; 1.10 : Now using matchable extension |
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118 | ; 1.9 : Added procedures pred-list and succ-list |
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119 | ; 1.8 : Added procedure node-info-set! |
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120 | ; 1.7 : Build script updated for better cross-platform compatibility |
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121 | ; 1.6 : Test infrastructure changed to use testbase |
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122 | ; 1.5 : Bug fixes in set-out-edges! and set-in-edges! [thanks to Andreas Scholta] |
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123 | ; 1.4 : License upgrade to GPL v3 |
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124 | ; 1.3 : Updated the roots procedure to match the documentation |
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125 | ; 1.2 : Minor changes to the setup script |
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126 | ; 1.1 : Added support for chicken-setup -test |
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127 | ; 1.0 : Initial release |
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128 | |
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129 | |
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130 | === License |
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131 | |
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132 | Copyright 2007-2018 Ivan Raikov. |
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133 | |
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134 | This program is free software: you can redistribute it and/or modify |
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135 | it under the terms of the GNU General Public License as published by |
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136 | the Free Software Foundation, either version 3 of the License, or (at |
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137 | your option) any later version. |
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138 | |
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139 | This program is distributed in the hope that it will be useful, but |
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140 | WITHOUT ANY WARRANTY; without even the implied warranty of |
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141 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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142 | General Public License for more details. |
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143 | |
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144 | A full copy of the GPL license can be found at |
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145 | <http://www.gnu.org/licenses/>. |
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146 | |
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