1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
|
/*!
\file vector/neta/components.c
\brief Network Analysis library - graph componets
Computes strongly and weakly connected components.
(C) 2009-2010 by Daniel Bundala, and the GRASS Development Team
This program is free software under the GNU General Public License
(>=v2). Read the file COPYING that comes with GRASS for details.
\author Daniel Bundala (Google Summer of Code 2009)
*/
#include <stdio.h>
#include <stdlib.h>
#include <grass/gis.h>
#include <grass/Vect.h>
#include <grass/glocale.h>
#include <grass/dgl/graph.h>
/*!
\brief Computes weekly connected components
\param graph input graph
\param[out] component list of components
\return number of components
\return -1 on failure
*/
int NetA_weakly_connected_components(dglGraph_s * graph, int *component)
{
int nnodes;
dglInt32_t *stack;
int *visited;
int stack_size, components;
dglInt32_t *cur_node;
dglNodeTraverser_s nt;
components = 0;
nnodes = dglGet_NodeCount(graph);
stack = (dglInt32_t *) G_calloc(nnodes + 1, sizeof(dglInt32_t));
visited = (int *)G_calloc(nnodes + 1, sizeof(int));
if (!stack || !visited) {
G_fatal_error(_("Out of memory"));
return -1;
}
dglNode_T_Initialize(&nt, graph);
for (cur_node = dglNode_T_First(&nt); cur_node;
cur_node = dglNode_T_Next(&nt)) {
dglInt32_t node_id = dglNodeGet_Id(graph, cur_node);
if (!visited[node_id]) {
visited[node_id] = 1;
stack[0] = node_id;
stack_size = 1;
component[node_id] = ++components;
while (stack_size) {
dglInt32_t *node, *edgeset, *edge;
dglEdgesetTraverser_s et;
node = dglGetNode(graph, stack[--stack_size]);
edgeset = dglNodeGet_OutEdgeset(graph, node);
dglEdgeset_T_Initialize(&et, graph, edgeset);
for (edge = dglEdgeset_T_First(&et); edge;
edge = dglEdgeset_T_Next(&et)) {
dglInt32_t to;
to = dglNodeGet_Id(graph, dglEdgeGet_Tail(graph, edge));
if (!visited[to]) {
visited[to] = 1;
component[to] = components;
stack[stack_size++] = to;
}
}
dglEdgeset_T_Release(&et);
}
}
}
dglNode_T_Release(&nt);
G_free(visited);
return components;
}
/*!
\brief Computes strongly connected components
\param graph input graph
\param[out] component list of components
\return number of components
\return -1 on failure
*/
int NetA_strongly_connected_components(dglGraph_s * graph, int *component)
{
int nnodes;
dglInt32_t *stack, *order;
int *visited, *processed;
int stack_size, order_size, components;
dglInt32_t *node;
dglNodeTraverser_s nt;
components = 0;
nnodes = dglGet_NodeCount(graph);
stack = (dglInt32_t *) G_calloc(nnodes + 1, sizeof(dglInt32_t));
order = (dglInt32_t *) G_calloc(nnodes + 1, sizeof(dglInt32_t));
visited = (int *)G_calloc(nnodes + 1, sizeof(int));
processed = (int *)G_calloc(nnodes + 1, sizeof(int));
if (!stack || !visited || !order || !processed) {
G_fatal_error(_("Out of memory"));
return -1;
}
order_size = 0;
dglNode_T_Initialize(&nt, graph);
for (node = dglNode_T_First(&nt); node; node = dglNode_T_Next(&nt)) {
dglInt32_t node_id = dglNodeGet_Id(graph, node);
component[node_id] = 0;
if (!visited[node_id]) {
visited[node_id] = 1;
stack[0] = node_id;
stack_size = 1;
while (stack_size) {
dglInt32_t *node, *edgeset, *edge;
dglEdgesetTraverser_s et;
dglInt32_t cur_node_id = stack[stack_size - 1];
if (processed[cur_node_id]) {
stack_size--;
order[order_size++] = cur_node_id;
continue;
}
processed[cur_node_id] = 1;
node = dglGetNode(graph, cur_node_id);
edgeset = dglNodeGet_OutEdgeset(graph, node);
dglEdgeset_T_Initialize(&et, graph, edgeset);
for (edge = dglEdgeset_T_First(&et); edge;
edge = dglEdgeset_T_Next(&et)) {
dglInt32_t to;
if (dglEdgeGet_Id(graph, edge) < 0)
continue; /*ignore backward edges */
to = dglNodeGet_Id(graph, dglEdgeGet_Tail(graph, edge));
if (!visited[to]) {
visited[to] = 1;
stack[stack_size++] = to;
}
}
dglEdgeset_T_Release(&et);
}
}
}
dglNode_T_Release(&nt);
while (order_size) {
dglInt32_t node_id = order[--order_size];
if (component[node_id])
continue;
components++;
component[node_id] = components;
stack[0] = node_id;
stack_size = 1;
while (stack_size) {
dglInt32_t *node, *edgeset, *edge;
dglEdgesetTraverser_s et;
dglInt32_t cur_node_id = stack[--stack_size];
node = dglGetNode(graph, cur_node_id);
edgeset = dglNodeGet_OutEdgeset(graph, node);
dglEdgeset_T_Initialize(&et, graph, edgeset);
for (edge = dglEdgeset_T_First(&et); edge;
edge = dglEdgeset_T_Next(&et)) {
dglInt32_t to;
if (dglEdgeGet_Id(graph, edge) > 0)
continue; /*ignore forward edges */
to = dglNodeGet_Id(graph, dglEdgeGet_Tail(graph, edge));
if (!component[to]) {
component[to] = components;
stack[stack_size++] = to;
}
}
dglEdgeset_T_Release(&et);
}
}
G_free(stack);
G_free(visited);
G_free(order);
G_free(processed);
return components;
}
|
