graph_generation.hh 20.1 KB
Newer Older
1
2
// graph-tool -- a general graph modification and manipulation thingy
//
Tiago Peixoto's avatar
Tiago Peixoto committed
3
// Copyright (C) 2006-2013 Tiago de Paula Peixoto <tiago@skewed.de>
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
//
// 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.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.

#ifndef GRAPH_GENERATION_HH
#define GRAPH_GENERATION_HH

21
22
23
#include "tr1_include.hh"
#include TR1_HEADER(unordered_map)
#include TR1_HEADER(tuple)
Tiago Peixoto's avatar
Tiago Peixoto committed
24
25
26
#include <boost/functional/hash.hpp>
#include <map>
#include <set>
27
28
#include <iostream>

29
#include "graph_util.hh"
30
#include "random.hh"
31

32
33
34
35
36
37
38
39
namespace graph_tool
{
using namespace std;
using namespace boost;

// desired vertex type, with desired j,k values and the index in the real graph
struct dvertex_t
{
40
    dvertex_t(): in_degree(0), out_degree(0) {}
41
42
43
44
45
46
47
    dvertex_t(size_t in, size_t out): in_degree(in), out_degree(out) {}
    dvertex_t(const pair<size_t,size_t>& deg): in_degree(deg.first),
                                               out_degree(deg.second) {}
    size_t index, in_degree, out_degree;
    bool operator==(const dvertex_t& other) const {return other.index == index;}
};

48
49
50
51
52
53
size_t hash_value(const dvertex_t& v)
{
    return v.index;
}


54
55
56
// used for verbose display
void print_progress(size_t current, size_t total, stringstream& str)
{
57
58
    size_t atom = (total > 200) ? total/100 : 1;
    if ( ( (current+1) % atom == 0) || (current + 1) == total)
59
60
61
62
    {
        for (size_t j = 0; j < str.str().length(); ++j)
            cout << "\b";
        str.str("");
63
64
        str << current+1 << " of " << total << " ("
            << (current+1)*100 / total << "%)";
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
        cout << str.str() << flush;
    }
}

void print_update(size_t current, stringstream& str)
{
    for (size_t j = 0; j < str.str().length(); ++j)
        cout << "\b";
    for (size_t j = 0; j < str.str().length(); ++j)
        cout << " ";
    for (size_t j = 0; j < str.str().length(); ++j)
        cout << "\b";
    str.str("");
    str << current;
    cout << str.str() << flush;
}

82

83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
//
// Generation strategies
// =====================
//
// Directed and undirected graphs have different generation strategies, which
// are defined in the classes below.

//
// Directed graph generation strategy
//

class DirectedStrat
{
public:
    typedef pair<size_t, size_t> deg_t; // degree type

    DirectedStrat(size_t N, bool no_parallel, bool no_self_loops)
        : _N(N), _no_parallel(no_parallel), _no_self_loops(no_self_loops)
    {
        if (_no_parallel)
Tiago Peixoto's avatar
Tiago Peixoto committed
103
            _max_deg = _no_self_loops ? _N - 1 : N;
104
105
106
107
        else
            _max_deg = numeric_limits<size_t>::max();
    }

Tiago Peixoto's avatar
Tiago Peixoto committed
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
    // check whether a degree sequence is graphical
    template <class DegSequence>
    bool is_graphical(DegSequence& d)
    {
        size_t one = _no_self_loops ? 1 : 0;

        size_t sum_out_deg = 0;
        size_t j = 0;
        for(typeof(d.begin()) di = d.begin(); di != d.end(); ++di)
        {
            size_t out_deg = di->first.second;
            size_t count = di->second;

            j += count;
            sum_out_deg += out_deg * count;

            size_t sum_in_deg = 0;
            typeof(d.begin()) dj_end = di; ++dj_end;
            for(typeof(d.begin()) dj = d.begin(); dj != dj_end; ++dj)
                sum_in_deg += min(dj->first.first, j - one)*dj->second;

            size_t sum_rest = 0;
            typeof(d.begin()) dj = di;
            for(++dj; dj != d.end(); ++dj)
                sum_rest += min(dj->first.first, j)*dj->second;

            if (sum_out_deg > sum_in_deg + sum_rest)
                return false;
        }
        return true;
    }

    // check whether a degree sequence is graphical, when parallel loops are
    // allowed but self-loops are not
    template <class DegSequence>
    bool is_graphical_parallel(DegSequence& d)
    {
        size_t sum_in_deg = 0;
        for(typeof(d.begin()) di = d.begin(); di != d.end(); ++di)
            sum_in_deg += di->first.first * di->second;
        for(typeof(d.begin()) di = d.begin(); di != d.end(); ++di)
        {
            if (di->first.second > sum_in_deg - di->first.first)
                return false;
        }
        return true;
    }

156
    // sample the degrees of all the vertices
Tiago Peixoto's avatar
Tiago Peixoto committed
157
158
    template <class DegSample>
    size_t SampleDegrees(vector<dvertex_t>& vertices, DegSample& deg_sample,
159
160
161
162
163
164
165
166
167
168
169
                         rng_t& rng, bool verbose)
    {
        stringstream str;
        size_t sum_j=0, sum_k=0;
        for(size_t i = 0; i < _N; ++i)
        {
            if (verbose)
                print_progress(i, _N, str);
            dvertex_t& v = vertices[i];
            do
            {
170
                tie(v.in_degree, v.out_degree) = deg_sample(i);
171
172
173
174
175
            }
            while (_no_parallel &&
                   (v.in_degree > _max_deg || v.out_degree > _max_deg));
            sum_j += v.in_degree;
            sum_k += v.out_degree;
176
            if (_no_parallel || _no_self_loops)
Tiago Peixoto's avatar
Tiago Peixoto committed
177
                _deg_seq[make_pair(v.in_degree, v.out_degree)]++;
178
179
180
181
182
183
        }

        if (verbose)
        {
            cout << "\nfixing average degrees. Total degree difference: "
                 << flush;
Tiago Peixoto's avatar
Tiago Peixoto committed
184
                str.str("");
185
186
        }

Tiago Peixoto's avatar
Tiago Peixoto committed
187
        // Sequence must be graphical. Re-sample random pairs until this holds
188
        tr1::uniform_int<size_t> vertex_sample(0, _N-1);
189
        size_t count = 0;
Tiago Peixoto's avatar
Tiago Peixoto committed
190
191
192
        while(sum_j != sum_k || (_no_parallel && !is_graphical(_deg_seq)) ||
              (_no_self_loops && !_no_parallel &&
               !is_graphical_parallel(_deg_seq)))
193
        {
194
195
            size_t i = vertex_sample(rng);
            dvertex_t& v = vertices[i];
196
            if (_no_parallel || _no_self_loops)
Tiago Peixoto's avatar
Tiago Peixoto committed
197
198
199
200
201
202
203
204
            {
                typeof(_deg_seq.begin()) iter =
                    _deg_seq.find(make_pair(v.in_degree, v.out_degree));
                iter->second--;
                if (iter->second == 0)
                    _deg_seq.erase(iter);
            }

205
206
207
208
            sum_j -= v.in_degree;
            sum_k -= v.out_degree;
            do
            {
209
                tie(v.in_degree, v.out_degree) = deg_sample(i);
210
211
212
213
214
            }
            while (_no_parallel &&
                   (v.in_degree > _max_deg || v.out_degree > _max_deg));
            sum_j += v.in_degree;
            sum_k += v.out_degree;
215
            if (_no_parallel || _no_self_loops)
Tiago Peixoto's avatar
Tiago Peixoto committed
216
                _deg_seq[make_pair(v.in_degree, v.out_degree)]++;
217
            if (verbose && (count % 100 == 0 || sum_j == sum_k))
218
                print_update(min(sum_j-sum_k, sum_k-sum_j), str);
219
220
221
222
223
            count++;
        }
        return sum_k;
    }

Tiago Peixoto's avatar
Tiago Peixoto committed
224
    struct deg_cmp
225
    {
Tiago Peixoto's avatar
Tiago Peixoto committed
226
227
228
229
230
231
232
        bool operator()(const deg_t& d1, const deg_t& d2) const
        {
            if (d1.second == d2.second)
                return d1.first > d2.first;
            return d1.second > d2.second;
        }
    };
233
234
235
236
237
238

private:
    size_t _N;
    bool _no_parallel;
    bool _no_self_loops;
    size_t _max_deg;
Tiago Peixoto's avatar
Tiago Peixoto committed
239
    map<deg_t, size_t, deg_cmp> _deg_seq;
240
241
242
243
244
245
246
247
248
};

//
// Undirected graph generation strategy
//

class UndirectedStrat
{
public:
Tiago Peixoto's avatar
Tiago Peixoto committed
249
    typedef size_t deg_t; // degree type
250
251
252
253
254
255
256
257
258
259

    UndirectedStrat(size_t N, bool no_parallel, bool no_self_loops)
        : _N(N), _no_parallel(no_parallel), _no_self_loops(no_self_loops)
    {
        if (_no_parallel)
            _max_deg = (_no_self_loops) ? _N - 1 : N;
        else
            _max_deg = numeric_limits<size_t>::max();
    }

Tiago Peixoto's avatar
Tiago Peixoto committed
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
    // check whether a degree sequence is graphical
    template <class DegSequence>
    bool is_graphical(DegSequence& d)
    {
        size_t one = (_no_self_loops) ? 1 : 0;
        size_t sum_deg = 0;
        size_t j = 0;
        for(typeof(d.begin()) di = d.begin(); di != d.end(); ++di)
        {
            j += di->second;
            sum_deg += di->first * di->second;
            size_t sum_rest = 0;
            typeof(d.begin()) dj = di;
            for(++dj; dj != d.end(); ++dj)
                sum_rest += min(dj->first, j)*dj->second;
            if (sum_deg > j*(j-one) + sum_rest)
                return false;
        }
        return true;
    }

    // check whether a degree sequence is graphical, when parallel loops are
    // allowed but self-loops are not
    template <class DegSequence>
    bool is_graphical_parallel(DegSequence& d)
    {
        size_t sum_deg = 0;
        for(typeof(d.begin()) di = d.begin(); di != d.end(); ++di)
            sum_deg += di->first * di->second;
        for(typeof(d.begin()) di = d.begin(); di != d.end(); ++di)
        {
            if (di->first > sum_deg - di->first)
                return false;
        }
        return true;
    }

297
    // samples the degress of all vertices
Tiago Peixoto's avatar
Tiago Peixoto committed
298
299
    template <class DegSample>
    size_t SampleDegrees(vector<dvertex_t>& vertices, DegSample& deg_sample,
300
301
302
303
                         rng_t& rng, bool verbose)
    {
        stringstream str;
        size_t sum_k=0;
Tiago Peixoto's avatar
Tiago Peixoto committed
304
        sum_k = 0;
305
306
307
308
309
310
311
        for(size_t i = 0; i < _N; ++i)
        {
            if (verbose)
                print_progress(i, _N, str);
            dvertex_t& v = vertices[i];
            do
            {
312
                v.out_degree = deg_sample(i, true);
313
314
315
            }
            while (_no_parallel && v.out_degree > _max_deg);
            sum_k += v.out_degree;
Tiago Peixoto's avatar
Tiago Peixoto committed
316
            _deg_seq[v.out_degree]++;
317
318
319
320
        }

        if (verbose)
        {
Tiago Peixoto's avatar
Tiago Peixoto committed
321
            cout << "\nFixing degree sequence: "
322
323
324
325
                 << flush;
            str.str("");
        }

Tiago Peixoto's avatar
Tiago Peixoto committed
326
327
328
        // sum_k must be an even number (2*num_edges), and degree sequence must
        // be graphical, if multiple edges are not allowed. Re-sample degrees
        // until this holds.
329
        tr1::uniform_int<size_t> vertex_sample(0, _N-1);
330
        size_t count = 0;
Tiago Peixoto's avatar
Tiago Peixoto committed
331
332
333
        while (sum_k % 2 != 0 || (_no_parallel && !is_graphical(_deg_seq)) ||
               (_no_self_loops && !_no_parallel &&
                !is_graphical_parallel(_deg_seq)))
334
        {
335
336
            size_t i = vertex_sample(rng);
            dvertex_t& v = vertices[i];
337
            if (_no_parallel || _no_self_loops)
Tiago Peixoto's avatar
Tiago Peixoto committed
338
339
340
341
342
343
            {
                typeof(_deg_seq.begin()) iter = _deg_seq.find(v.out_degree);
                iter->second--;
                if(iter->second == 0)
                    _deg_seq.erase(iter);
            }
344
345
346
            sum_k -= v.out_degree;
            do
            {
347
                v.out_degree = deg_sample(i, true);
348
349
350
            }
            while (_no_parallel && (v.out_degree > _max_deg));
            sum_k +=  v.out_degree;
351
            if (_no_parallel || _no_self_loops)
Tiago Peixoto's avatar
Tiago Peixoto committed
352
                _deg_seq[v.out_degree]++;
353
354
355
356
            if (verbose && (count % 100 || sum_k % 2 == 0))
                print_update(sum_k, str);
            count++;
        }
Tiago Peixoto's avatar
Tiago Peixoto committed
357
        return sum_k/2;
358
359
360
361
362
363
364
    }

private:
    size_t _N;
    bool _no_parallel;
    bool _no_self_loops;
    size_t _max_deg;
Tiago Peixoto's avatar
Tiago Peixoto committed
365
    map<size_t, size_t, greater<size_t> > _deg_seq;
366
367
368
};

//
Tiago Peixoto's avatar
Tiago Peixoto committed
369
370
// Main Algorithm
// ==============
371
//
Tiago Peixoto's avatar
Tiago Peixoto committed
372
// generates a directed or undirected graph with given degree distribution
373

Tiago Peixoto's avatar
Tiago Peixoto committed
374
375
template <class Cmp>
struct cmp_in
376
{
Tiago Peixoto's avatar
Tiago Peixoto committed
377
378
    bool operator()(const pair<size_t,size_t>& v1,
                    const pair<size_t,size_t>& v2) const
379
    {
Tiago Peixoto's avatar
Tiago Peixoto committed
380
381
382
        if (v1.first == v2.first)
            return cmp(v1.second, v2.second);
        return cmp(v1.first, v2.first);
383
    }
Tiago Peixoto's avatar
Tiago Peixoto committed
384
    Cmp cmp;
385
386
};

Tiago Peixoto's avatar
Tiago Peixoto committed
387
388
template <class Cmp>
struct cmp_out
389
{
Tiago Peixoto's avatar
Tiago Peixoto committed
390
391
    bool operator()(const pair<size_t,size_t>& v1,
                    const pair<size_t,size_t>& v2) const
392
    {
Tiago Peixoto's avatar
Tiago Peixoto committed
393
394
395
        if (v1.second == v2.second)
            return cmp(v1.first, v2.first);
        return cmp(v1.second, v2.second);
396
    }
Tiago Peixoto's avatar
Tiago Peixoto committed
397
    Cmp cmp;
398
399
};

Tiago Peixoto's avatar
Tiago Peixoto committed
400
401
402
403
404
405
template <class Graph>
pair<size_t, size_t> get_deg(dvertex_t& v, Graph& g)
{
    return make_pair(v.in_degree - in_degreeS()(vertex(v.index, g), g),
                     v.out_degree - out_degree(vertex(v.index, g), g));
}
406

407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
template <class Graph>
bool is_source(const pair<size_t, size_t>& deg)
{
    return deg.second > 0;
}

template <class Graph>
bool is_target(const pair<size_t, size_t>& deg)
{
    if (is_directed::apply<Graph>::type::value)
        return deg.first > 0;
    else
        return is_source<Graph>(deg);
}


template <class Vset, class Targets, class Sources, class Graph>
bool update_deg(size_t t_i, const pair<size_t, size_t>& deg, Vset& vset,
425
                Targets& targets, Sources& sources, Graph&)
426
427
428
429
430
431
432
433
434
{
    if (is_source<Graph>(deg))
        sources.insert(deg);
    if (is_target<Graph>(deg))
        targets.insert(deg);
    vset[deg].push_back(t_i);
    return true;
}

435
struct gen_graph
436
{
Tiago Peixoto's avatar
Tiago Peixoto committed
437
438
    template <class Graph, class DegSample>
    void operator()(Graph& g, size_t N, DegSample& deg_sample, bool no_parallel,
439
                    bool no_self_loops, rng_t& rng, bool verbose, bool verify)
440
441
442
443
444
        const
    {
        typename property_map<Graph,vertex_index_t>::type vertex_index =
            get(vertex_index_t(), g);

Tiago Peixoto's avatar
Tiago Peixoto committed
445
        // figure out the necessary strategy
446
447
        typedef typename mpl::if_<typename is_directed::apply<Graph>::type,
                                  DirectedStrat,
448
449
450
451
452
453
454
455
456
                                  UndirectedStrat>::type gen_strat_t;

        gen_strat_t gen_strat(N, no_parallel, no_self_loops);
        stringstream str; // used for verbose status

        if (verbose)
            cout << "adding vertices: " << flush;

        vector<dvertex_t> vertices(N);
Tiago Peixoto's avatar
Tiago Peixoto committed
457
458
        for(size_t i = 0; i < N; ++i)
            vertices[i].index = vertex_index[add_vertex(g)];
459

Tiago Peixoto's avatar
Tiago Peixoto committed
460
461
        // sample the N (j,k) pairs
        size_t E = gen_strat.SampleDegrees(vertices, deg_sample, rng, verbose);
462

463
        // source and target degree lists
Tiago Peixoto's avatar
Tiago Peixoto committed
464
465
466
        typedef pair<size_t, size_t> deg_t;
        set<deg_t, cmp_out<greater<size_t> > > sources;
        set<deg_t, cmp_in<greater<size_t> > > targets;
467
468
469

        // vertices with a given degree
        tr1::unordered_map<deg_t, vector<size_t>,
470
                           hash<deg_t> > vset;
471

472
        size_t num_e = 0;
Tiago Peixoto's avatar
Tiago Peixoto committed
473
        for (size_t i = 0; i < vertices.size();  ++i)
474
        {
Tiago Peixoto's avatar
Tiago Peixoto committed
475
            deg_t deg = get_deg(vertices[i], g);
476
477
478
479
480
481
482

            if (is_source<Graph>(deg))
                sources.insert(deg);
            if (is_target<Graph>(deg))
                targets.insert(deg);
            if (is_target<Graph>(deg) || is_source<Graph>(deg))
                vset[deg].push_back(i);
483
484
485
486
        }

        if (verbose)
        {
Tiago Peixoto's avatar
Tiago Peixoto committed
487
            cout << endl << "adding edges: " << flush;
488
489
490
            str.str("");
        }

491
        vector<size_t> skip;
492

Tiago Peixoto's avatar
Tiago Peixoto committed
493
494
495
496
497
498
499
        // connect edges: from sources with the largest in-degree to the ones
        // with largest out-degree
        while (!sources.empty())
        {
            // find source. The out-degree must be non-zero, and there must be a
            // vertex with the chosen degree.
            deg_t s_deg = *sources.begin();
500
501
502
            typeof(vset.begin()) sv_iter = vset.find(s_deg);
            if (s_deg.second == 0 || sv_iter == vset.end() ||
                sv_iter->second.empty())
503
            {
Tiago Peixoto's avatar
Tiago Peixoto committed
504
505
                sources.erase(sources.begin());
                continue;
506
507
            }

508
509
            vector<size_t>& s_list = sv_iter->second;
            size_t s_i = s_list.front();
Tiago Peixoto's avatar
Tiago Peixoto committed
510
511
            typename graph_traits<Graph>::vertex_descriptor s =
                vertex(vertices[s_i].index, g);
512

513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
            deg_t ns_deg = get_deg(vertices[s_i], g);
            if (ns_deg != s_deg)
            {
                swap(s_list.back(), s_list.front());
                s_list.pop_back();
                update_deg(s_i, ns_deg, vset, targets, sources, g);
                continue;
            }

            // find the targets.
            // we will keep an iterator to the current target degree
            typeof(targets.begin()) t_iter = targets.begin();
            typeof(vset.begin()) v_iter = vset.find(*t_iter);
            while (v_iter == vset.end() || v_iter->second.empty())
            {
                targets.erase(t_iter);
                t_iter = targets.begin();
                v_iter = vset.find(*t_iter);
            }

            skip.clear();
            skip.push_back(s_i);

            if (no_self_loops)
            {
                swap(s_list.back(), s_list.front());
                s_list.pop_back();
            }

Tiago Peixoto's avatar
Tiago Peixoto committed
542
            while (s_deg.second > 0)
543
            {
544
545
546
547
                //assert(!targets.empty());
                //assert(t_iter != targets.end());

                while (v_iter == vset.end() || v_iter->second.empty())
548
                {
549
550
                    ++t_iter;
                    v_iter = vset.find(*t_iter);
551
552
                }

553
                deg_t t_deg = *t_iter;
554

555
556
557
558
559
560
                vector<size_t>& v_list = v_iter->second;

                size_t t_i = v_list.front();

                deg_t nt_deg = get_deg(vertices[t_i], g);
                if (nt_deg != t_deg)
561
                {
562
563
564
565
566
567
                    swap(v_list.back(), v_list.front());
                    v_list.pop_back();
                    update_deg(t_i, nt_deg, vset, targets, sources, g);
                    //t_iter = targets.begin();
                    //v_iter = vset.find(*t_iter);
                    continue;
568
569
                }

570
571
572
573
574
575
                // remove target from vertex list, and get new t_i
                skip.push_back(t_i);

                swap(v_list.back(), v_list.front());
                v_list.pop_back();

Tiago Peixoto's avatar
Tiago Peixoto committed
576
577
                typename graph_traits<Graph>::vertex_descriptor t =
                    vertex(vertices[t_i].index, g);
578

579
580
581
                if ((s == t) && (!is_directed::apply<Graph>::type::value &&
                                 s_deg.second < 2))
                    continue;
582

Tiago Peixoto's avatar
Tiago Peixoto committed
583
                add_edge(s, t, g);
584
                s_deg = get_deg(vertices[s_i], g);
585

586
587
                // if parallel edges are allowed, we should update the target
                // list right away
Tiago Peixoto's avatar
Tiago Peixoto committed
588
589
                if (!no_parallel)
                {
590
591
592
593
594
595
596
597
598
599
600
                    for (size_t i = 0; i < skip.size(); ++i)
                    {
                        if (no_self_loops && skip[i] == s_i)
                            continue;
                        update_deg(skip[i],
                                   get_deg(vertices[skip[i]], g), vset,
                                   targets, sources, g);
                    }
                    skip.clear();
                    if (no_self_loops)
                        skip.push_back(s_i);
Tiago Peixoto's avatar
Tiago Peixoto committed
601
602
603
604
605
                }
                if (verbose)
                    print_progress(num_e++, E, str);
            }

606
            if (!s_list.empty() && s_list.front() == s_i)
Tiago Peixoto's avatar
Tiago Peixoto committed
607
            {
608
609
                swap(s_list.back(), s_list.front());
                s_list.pop_back();
Tiago Peixoto's avatar
Tiago Peixoto committed
610
            }
611
612
613
614
615
616
617

            // update modified degrees
            for (size_t i = 0; i < skip.size(); ++i)
                update_deg(skip[i],
                           get_deg(vertices[skip[i]], g),
                           vset, targets, sources, g);
       }
618
        if (verbose)
Tiago Peixoto's avatar
Tiago Peixoto committed
619
            cout << endl;
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643

        if (verify)
        {
            for (size_t i = 0; i < vertices.size(); ++i)
            {
                deg_t dseq = make_pair(vertices[i].in_degree,
                                       vertices[i].out_degree);
                deg_t deg = make_pair(in_degreeS()(vertex(i, g), g),
                                      out_degree(vertex(i, g), g));
                if (deg != dseq)
                    throw GraphException("Graph does not match the desired "
                                         "sequence! Vertex " +
                                         lexical_cast<string>(i) +
                                         ", wanted: " +
                                         lexical_cast<string>(dseq.first) +
                                         " " +
                                         lexical_cast<string>(dseq.second) +
                                         ", got: " +
                                         lexical_cast<string>(deg.first) +
                                         " " +
                                         lexical_cast<string>(deg.second) +
                                         " This is a bug.");
            }
        }
644
645
646
647
648
649
    }
};

} // graph_tool namespace

#endif // GRAPH_GENERATION_HH