/**
* \ingroup python_interface_arpack
* \brief Allocates a new ARPACK parameters object
*/
PyObject* igraphmodule_ARPACKOptions_new() {
igraphmodule_ARPACKOptionsObject* self;
self=PyObject_New(igraphmodule_ARPACKOptionsObject,
&igraphmodule_ARPACKOptionsType);
if (self) {
igraph_arpack_options_init(&self->params);
igraph_arpack_options_init(&self->params_out);
}
return (PyObject*)self;
}
int main() {
igraph_t g;
igraph_vector_t v, weights;
long int i;
igraph_real_t value;
igraph_arpack_options_t options;
igraph_star(&g, 100, IGRAPH_STAR_UNDIRECTED, 0);
igraph_arpack_options_init(&options);
igraph_vector_init(&v, 0);
igraph_eigenvector_centrality(&g, &v, &value, /*directed=*/ 0,
/*scale=*/0, /*weights=*/0,
&options);
if (options.info != 0) {
return 1;
}
for (i=0; i<igraph_vector_size(&v); i++) {
printf(" %.3f", fabs(VECTOR(v)[i]));
}
printf("\n");
igraph_destroy(&g);
/* Special cases: check for empty graph */
igraph_empty(&g, 10, 0);
igraph_eigenvector_centrality(&g, &v, &value, 0, 0, 0, &options);
if (value != 0.0) {
return 1;
}
for (i=0; i<igraph_vector_size(&v); i++) {
printf(" %.2f", fabs(VECTOR(v)[i]));
}
printf("\n");
igraph_destroy(&g);
/* Special cases: check for full graph, zero weights */
igraph_full(&g, 10, 0, 0);
igraph_vector_init(&weights, 45);
igraph_vector_fill(&weights, 0);
igraph_eigenvector_centrality(&g, &v, &value, 0, 0, &weights, &options);
igraph_vector_destroy(&weights);
if (value != 0.0) {
return 2;
}
for (i=0; i<igraph_vector_size(&v); i++) {
printf(" %.2f", fabs(VECTOR(v)[i]));
}
printf("\n");
igraph_destroy(&g);
igraph_vector_destroy(&v);
return 0;
}
VALUE cIGraph_community_leading_eigenvector_naive(VALUE self, VALUE steps){
igraph_t *graph;
igraph_vector_t membership;
igraph_matrix_t *merges = malloc(sizeof(igraph_matrix_t));
igraph_arpack_options_t arpack_opt;
igraph_arpack_options_init(&arpack_opt);
int i,groupid,max_groupid;
VALUE groups, group, res;
Data_Get_Struct(self, igraph_t, graph);
igraph_matrix_init(merges,0,0);
igraph_vector_init(&membership,0);
igraph_community_leading_eigenvector_naive(graph,merges,&membership,
NUM2INT(steps), &arpack_opt);
max_groupid = 0;
for(i=0;i<igraph_vector_size(&membership);i++){
if(VECTOR(membership)[i] > max_groupid)
max_groupid = VECTOR(membership)[i];
}
groups = rb_ary_new();
for(i=0;i<max_groupid+1;i++){
rb_ary_push(groups,rb_ary_new());
}
for(i=0;i<igraph_vector_size(&membership);i++){
groupid = VECTOR(membership)[i];
if(groupid == -1)
groupid = 0;
group = RARRAY_PTR(groups)[groupid];
rb_ary_push(group,cIGraph_get_vertex_object(self, i));
}
res = rb_ary_new3(2,groups,
Data_Wrap_Struct(cIGraphMatrix, 0,
cIGraph_matrix_free, merges));
igraph_vector_destroy(&membership);
return res;
}
int main() {
igraph_t small, big;
igraph_matrix_t small_coords, big_coords, merged_coords;
igraph_vector_ptr_t graph_ptr, coords_ptr;
igraph_arpack_options_t arpack_opts;
/* To make things reproducible */
igraph_rng_seed(igraph_rng_default(), 42);
igraph_small(&big, 10, IGRAPH_UNDIRECTED,
0,1, 1,2, 2,3, 3,4, 4,5, 5,6, 6,7, 7,8, 8,9, 9,0,
-1);
igraph_small(&small, 3, IGRAPH_UNDIRECTED,
0,1, 1,2, 2,0,
-1);
igraph_arpack_options_init(&arpack_opts);
igraph_matrix_init(&big_coords, 0, 0);
igraph_layout_mds(&big, &big_coords, /*dist=*/ 0, /*dim=*/ 2,
&arpack_opts);
igraph_matrix_init(&small_coords, 0, 0);
igraph_layout_mds(&small, &small_coords, /*dist=*/ 0, /*dim=*/ 2,
&arpack_opts);
igraph_vector_ptr_init(&graph_ptr, 2);
igraph_vector_ptr_init(&coords_ptr, 2);
igraph_matrix_init(&merged_coords, 0, 0);
VECTOR(graph_ptr)[0] = &big;
VECTOR(graph_ptr)[1] = &small;
VECTOR(coords_ptr)[0] = &big_coords;
VECTOR(coords_ptr)[1] = &small_coords;
igraph_layout_merge_dla(&graph_ptr, &coords_ptr, &merged_coords);
igraph_matrix_print(&merged_coords);
igraph_matrix_destroy(&merged_coords);
igraph_matrix_destroy(&small_coords);
igraph_matrix_destroy(&big_coords);
igraph_vector_ptr_destroy(&graph_ptr);
igraph_vector_ptr_destroy(&coords_ptr);
igraph_destroy(&small);
igraph_destroy(&big);
#ifdef __APPLE__
return 0;
#else
return 77;
#endif
}
/* call-seq:
* graph.eigenvector_centrality(scale, weights) -> Array
*
* Returns a two-element arrar, the first element of which is an Array of
* eigenvector centrality scores for graph, and the second of which is the
* eigenvalue.
*
* scale is a boolean value. If true, the scores will be weighted so that the
* absolute value of the maximum centrality is one.
*
* weights is an Array giving the weights of the edges. If nil, the edges are unweighted.
*/
VALUE cIGraph_eigenvector_centrality(VALUE self, VALUE scale, VALUE weights) {
int i;
igraph_t *graph;
igraph_vector_t vec;
igraph_real_t val;
igraph_vector_t wgts;
igraph_arpack_options_t arpack_opt;
igraph_bool_t sc = 0;
VALUE eigenvector = rb_ary_new();
VALUE rb_res = rb_ary_new();
IGRAPH_FINALLY(igraph_vector_destroy, &vec);
IGRAPH_FINALLY(igraph_vector_destroy, &wgts);
IGRAPH_CHECK(igraph_vector_init(&vec,0));
IGRAPH_CHECK(igraph_vector_init(&wgts,0));
igraph_arpack_options_init(&arpack_opt);
if (scale == Qtrue) sc = 1;
Data_Get_Struct(self, igraph_t, graph);
if (weights == Qnil) {
IGRAPH_CHECK(igraph_eigenvector_centrality(graph, &vec, &val, sc, NULL, &arpack_opt));
} else {
for(i = 0; i < RARRAY_LEN(weights); i++)
IGRAPH_CHECK(igraph_vector_push_back(&wgts, NUM2DBL(RARRAY_PTR(weights)[i])));
IGRAPH_CHECK(igraph_eigenvector_centrality(graph, &vec, &val, sc, &wgts, &arpack_opt));
}
for(i = 0; i < igraph_vector_size(&vec); i++)
rb_ary_push(eigenvector, rb_float_new(VECTOR(vec)[i]));
igraph_vector_destroy(&vec);
igraph_vector_destroy(&wgts);
rb_ary_push(rb_res, eigenvector);
rb_ary_push(rb_res, rb_float_new(val));
IGRAPH_FINALLY_CLEAN(2);
return rb_res;
}
int main() {
igraph_t g;
igraph_vector_t v, res, reset, weights;
igraph_arpack_options_t arpack_options;
igraph_real_t value;
int ret;
igraph_pagerank_power_options_t power_options;
/* Test graphs taken from http://www.iprcom.com/papers/pagerank/ */
igraph_vector_init(&v, 10);
VECTOR(v)[0]=0; VECTOR(v)[1]=1;
VECTOR(v)[2]=1; VECTOR(v)[3]=2;
VECTOR(v)[4]=2; VECTOR(v)[5]=0;
VECTOR(v)[6]=3; VECTOR(v)[7]=2;
VECTOR(v)[8]=0; VECTOR(v)[9]=2;
igraph_create(&g, &v, 0, 1);
igraph_vector_init(&res, 0);
oldwarn=igraph_set_warning_handler(warning_handler_stdout);
igraph_pagerank_old(&g, &res, igraph_vss_all(), 1, 1000, 0.001, 0.85, 0);
print_vector(&res, stdout);
igraph_vector_destroy(&res);
igraph_vector_destroy(&v);
igraph_destroy(&g);
igraph_vector_init(&v, 28);
VECTOR(v)[ 0]=0; VECTOR(v)[ 1]=1;
VECTOR(v)[ 2]=0; VECTOR(v)[ 3]=2;
VECTOR(v)[ 4]=0; VECTOR(v)[ 5]=3;
VECTOR(v)[ 6]=1; VECTOR(v)[ 7]=0;
VECTOR(v)[ 8]=2; VECTOR(v)[ 9]=0;
VECTOR(v)[10]=3; VECTOR(v)[11]=0;
VECTOR(v)[12]=3; VECTOR(v)[13]=4;
VECTOR(v)[14]=3; VECTOR(v)[15]=5;
VECTOR(v)[16]=3; VECTOR(v)[17]=6;
VECTOR(v)[18]=3; VECTOR(v)[19]=7;
VECTOR(v)[20]=4; VECTOR(v)[21]=0;
VECTOR(v)[22]=5; VECTOR(v)[23]=0;
VECTOR(v)[24]=6; VECTOR(v)[25]=0;
VECTOR(v)[26]=7; VECTOR(v)[27]=0;
igraph_create(&g, &v, 0, 1);
igraph_vector_init(&res, 0);
igraph_pagerank_old(&g, &res, igraph_vss_all(), 1, 10000, 0.0001, 0.85, 0);
print_vector(&res, stdout);
igraph_vector_destroy(&res);
igraph_vector_destroy(&v);
igraph_destroy(&g);
igraph_set_warning_handler(oldwarn);
/* New PageRank */
igraph_star(&g, 11, IGRAPH_STAR_UNDIRECTED, 0);
igraph_vector_init(&res, 0);
igraph_arpack_options_init(&arpack_options);
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_ARPACK, &res, 0,
igraph_vss_all(), 0, 0.85, 0, &arpack_options);
print_vector(&res, stdout);
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_PRPACK, &res, 0,
igraph_vss_all(), 0, 0.85, 0, 0);
print_vector(&res, stdout);
/* Check twice more for consistency */
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_ARPACK, &res, 0,
igraph_vss_all(), 0, 0.85, 0, &arpack_options);
print_vector(&res, stdout);
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_PRPACK, &res, 0,
igraph_vss_all(), 0, 0.85, 0, 0);
print_vector(&res, stdout);
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_ARPACK, &res, 0,
igraph_vss_all(), 0, 0.85, 0, &arpack_options);
print_vector(&res, stdout);
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_PRPACK, &res, 0,
igraph_vss_all(), 0, 0.85, 0, 0);
print_vector(&res, stdout);
/* Check personalized PageRank */
igraph_personalized_pagerank_vs(&g, IGRAPH_PAGERANK_ALGO_ARPACK, &res, 0,
igraph_vss_all(), 0, 0.5,
igraph_vss_1(1), 0, &arpack_options);
print_vector(&res, stdout);
igraph_personalized_pagerank_vs(&g, IGRAPH_PAGERANK_ALGO_PRPACK, &res, 0,
igraph_vss_all(), 0, 0.5,
igraph_vss_1(1), 0, 0);
print_vector(&res, stdout);
/* Errors */
power_options.niter = -1; power_options.eps=0.0001;
igraph_set_error_handler(igraph_error_handler_ignore);
igraph_set_warning_handler(igraph_warning_handler_ignore);
ret=igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_POWER, &res,
/*value=*/ 0, igraph_vss_all(), 1, 0.85,
/*weights=*/ 0, &power_options);
if (ret != IGRAPH_EINVAL) {
return 1;
}
power_options.niter=10000; power_options.eps=-1;
ret=igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_POWER, &res,
/*value=*/ 0, igraph_vss_all(), 1, 0.85,
/*weights=*/ 0, &power_options);
if (ret != IGRAPH_EINVAL) {
return 2;
}
power_options.niter=10000; power_options.eps=0.0001;
ret=igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_POWER, &res,
/*value=*/ 0, igraph_vss_all(), 1, 1.2,
/*weights=*/ 0, &power_options);
if (ret != IGRAPH_EINVAL) {
return 3;
}
igraph_vector_init(&reset, 2);
ret=igraph_personalized_pagerank(&g, IGRAPH_PAGERANK_ALGO_ARPACK, &res, 0,
igraph_vss_all(), 0, 0.85, &reset, 0,
&arpack_options);
if (ret != IGRAPH_EINVAL) {
return 4;
}
ret=igraph_personalized_pagerank(&g, IGRAPH_PAGERANK_ALGO_PRPACK, &res, 0,
igraph_vss_all(), 0, 0.85, &reset, 0, 0);
if (ret != IGRAPH_EINVAL) {
return 4;
}
igraph_vector_resize(&reset, 10);
igraph_vector_fill(&reset, 0);
ret=igraph_personalized_pagerank(&g, IGRAPH_PAGERANK_ALGO_ARPACK,
&res, 0, igraph_vss_all(), 0, 0.85,
&reset, 0, &arpack_options);
if (ret != IGRAPH_EINVAL) {
return 5;
}
ret=igraph_personalized_pagerank(&g, IGRAPH_PAGERANK_ALGO_PRPACK,
&res, 0, igraph_vss_all(), 0, 0.85,
&reset, 0, 0);
if (ret != IGRAPH_EINVAL) {
return 5;
}
igraph_vector_destroy(&reset);
igraph_destroy(&g);
igraph_set_error_handler(igraph_error_handler_abort);
/* Special cases: check for empty graph */
igraph_empty(&g, 10, 0);
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_ARPACK, &res, &value,
igraph_vss_all(), 1, 0.85, 0, &arpack_options);
if (value != 1.0) {
return 6;
}
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_PRPACK, &res, &value,
igraph_vss_all(), 1, 0.85, 0, 0);
if (value != 1.0) {
return 6;
}
print_vector(&res, stdout);
igraph_destroy(&g);
/* Special cases: check for full graph, zero weights */
igraph_full(&g, 10, 0, 0);
igraph_vector_init(&v, 45);
igraph_vector_fill(&v, 0);
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_ARPACK, &res, &value,
igraph_vss_all(), 1, 0.85, &v, &arpack_options);
if (value != 1.0) {
return 7;
}
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_PRPACK, &res, &value,
igraph_vss_all(), 1, 0.85, &v, 0);
if (value != 1.0) {
return 7;
}
igraph_vector_destroy(&v);
print_vector(&res, stdout);
igraph_destroy(&g);
/* Another test case for PageRank (bug #792352) */
igraph_small(&g, 9, 1, 0, 5, 1, 5, 2, 0, 3, 1, 5, 4, 5, 7, 6, 0, 8, 0, 8, 1, -1);
igraph_vector_init(&weights, 9);
VECTOR(weights)[0] = 4; VECTOR(weights)[1] = 5; VECTOR(weights)[2] = 5;
VECTOR(weights)[3] = 4; VECTOR(weights)[4] = 4; VECTOR(weights)[5] = 4;
VECTOR(weights)[6] = 3; VECTOR(weights)[7] = 4; VECTOR(weights)[8] = 4;
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_ARPACK, &res, 0,
igraph_vss_all(), 1, 0.85, &weights, &arpack_options);
print_vector(&res, stdout);
igraph_pagerank(&g, IGRAPH_PAGERANK_ALGO_PRPACK, &res, 0,
igraph_vss_all(), 1, 0.85, &weights, 0);
print_vector(&res, stdout);
igraph_vector_destroy(&weights);
igraph_destroy(&g);
igraph_vector_destroy(&res);
return 0;
}
int main() {
igraph_matrix_t A;
igraph_matrix_t values, vectors;
igraph_arpack_options_t options;
cb2_data_t data = { &A };
int i, j;
igraph_rng_seed(igraph_rng_default(), 42 * 42);
igraph_matrix_init(&A, DIM, DIM);
for (i=0; i<DIM; i++) {
for (j=0; j<DIM; j++) {
MATRIX(A, i, j) = igraph_rng_get_integer(igraph_rng_default(), -10, 10);
}
}
igraph_arpack_options_init(&options);
options.n=DIM;
options.start=0;
options.nev=4;
options.ncv=9;
options.which[0]='L' ; options.which[1]='M';
igraph_matrix_init(&values, 0, 0);
igraph_matrix_init(&vectors, options.n, 1);
igraph_arpack_rnsolve(cb2, /*extra=*/ &data, &options, /*storage=*/ 0,
&values, &vectors);
if (MATRIX(values, 2, 1) > 0) {
MATRIX(values, 2, 1) = -MATRIX(values, 2, 1);
MATRIX(values, 3, 1) = -MATRIX(values, 3, 1);
}
igraph_matrix_print(&values);
printf("---\n");
igraph_matrix_print(&vectors);
printf("---\n");
/* -------------- */
options.nev=3;
options.which[0]='L' ; options.which[1]='M';
igraph_arpack_rnsolve(cb2, /*extra=*/ &data, &options, /*storage=*/ 0,
&values, &vectors);
if (MATRIX(values, 2, 1) > 0) {
MATRIX(values, 2, 1) = -MATRIX(values, 2, 1);
}
igraph_matrix_print(&values);
printf("---\n");
igraph_matrix_print(&vectors);
printf("---\n");
/* -------------- */
options.nev=3;
options.which[0]='S' ; options.which[1]='R';
igraph_arpack_rnsolve(cb2, /*extra=*/ &data, &options, /*storage=*/ 0,
&values, &vectors);
igraph_matrix_print(&values);
printf("---\n");
igraph_matrix_print(&vectors);
printf("---\n");
/* -------------- */
options.nev=3;
options.which[0]='L' ; options.which[1]='I';
igraph_arpack_rnsolve(cb2, /*extra=*/ &data, &options, /*storage=*/ 0,
&values, &vectors);
igraph_matrix_print(&values);
printf("---\n");
igraph_matrix_print(&vectors);
printf("---\n");
/* -------------- */
igraph_matrix_destroy(&values);
igraph_matrix_destroy(&vectors);
igraph_matrix_destroy(&A);
return 0;
}
int main() {
igraph_t g;
igraph_matrix_t merges;
igraph_vector_t membership;
long int i, j;
igraph_bool_t split;
igraph_vector_t x;
igraph_real_t val;
igraph_arpack_options_t options;
/* Zachary Karate club */
igraph_small(&g, 0, IGRAPH_UNDIRECTED,
0, 1, 0, 2, 0, 3, 0, 4, 0, 5,
0, 6, 0, 7, 0, 8, 0, 10, 0, 11,
0, 12, 0, 13, 0, 17, 0, 19, 0, 21,
0, 31, 1, 2, 1, 3, 1, 7, 1, 13,
1, 17, 1, 19, 1, 21, 1, 30, 2, 3,
2, 7, 2, 8, 2, 9, 2, 13, 2, 27,
2, 28, 2, 32, 3, 7, 3, 12, 3, 13,
4, 6, 4, 10, 5, 6, 5, 10, 5, 16,
6, 16, 8, 30, 8, 32, 8, 33, 9, 33,
13, 33, 14, 32, 14, 33, 15, 32, 15, 33,
18, 32, 18, 33, 19, 33, 20, 32, 20, 33,
22, 32, 22, 33, 23, 25, 23, 27, 23, 29,
23, 32, 23, 33, 24, 25, 24, 27, 24, 31,
25, 31, 26, 29, 26, 33, 27, 33, 28, 31,
28, 33, 29, 32, 29, 33, 30, 32, 30, 33,
31, 32, 31, 33, 32, 33,
-1);
/* Make one step with all methods */
igraph_matrix_init(&merges, 0, 0);
igraph_vector_init(&membership, 0);
igraph_vector_init(&x, 0);
igraph_arpack_options_init(&options);
igraph_community_leading_eigenvector_naive(&g, &merges, &membership, 1, &options);
print_matrix(&merges);
print_vector(&membership);
igraph_community_leading_eigenvector(&g, &merges, &membership, 1, &options);
print_matrix(&merges);
print_vector(&membership);
igraph_vector_null(&membership);
igraph_community_leading_eigenvector_step(&g, &membership, 0, &split,
&x, &val, &options, 0);
print_vector(&membership);
print_vector(&x);
printf("\n");
/* Make all the steps */
igraph_community_leading_eigenvector(&g, &merges, &membership, igraph_vcount(&g),
&options);
print_matrix(&merges);
print_vector(&membership);
/* Try to make one more step from here, should fail */
for (i=0; i<igraph_matrix_nrow(&merges)+1; i++) {
igraph_community_leading_eigenvector_step(&g, &membership,
i, &split, &x, &val, &options, 0);
if (split) {
printf("Impossible, community %li splitted.\n", i);
return 1;
}
}
igraph_vector_destroy(&x);
igraph_vector_destroy(&membership);
igraph_matrix_destroy(&merges);
igraph_destroy(&g);
return 0;
}
VALUE cIGraph_community_leading_eigenvector_step(VALUE self, VALUE membership, VALUE community){
igraph_t *graph;
igraph_vector_t membership_vec;
igraph_vector_t eigenvector;
igraph_real_t eigenvalue;
igraph_bool_t split;
int i,j,groupid,max_groupid,vid;
igraph_arpack_options_t arpack_opt;
igraph_arpack_options_init(&arpack_opt);
VALUE groups, group, res, eigenvector_a, obj;
Data_Get_Struct(self, igraph_t, graph);
igraph_vector_init(&membership_vec,igraph_vcount(graph));
igraph_vector_init(&eigenvector,0);
for(i=0;i<RARRAY_LEN(membership);i++){
group = RARRAY_PTR(membership)[i];
for(j=0;j<RARRAY_LEN(group);j++){
obj = RARRAY_PTR(group)[j];
vid = cIGraph_get_vertex_id(self,obj);
VECTOR(membership_vec)[vid] = i;
}
}
igraph_community_leading_eigenvector_step(graph,&membership_vec,
NUM2INT(community),
&split,&eigenvector,&eigenvalue,&arpack_opt,NULL);
max_groupid = 0;
for(i=0;i<igraph_vector_size(&membership_vec);i++){
if(VECTOR(membership_vec)[i] > max_groupid)
max_groupid = VECTOR(membership_vec)[i];
}
groups = rb_ary_new();
for(i=0;i<max_groupid+1;i++){
rb_ary_push(groups,rb_ary_new());
}
for(i=0;i<igraph_vector_size(&membership_vec);i++){
groupid = VECTOR(membership_vec)[i];
if(groupid == -1)
groupid = 0;
group = RARRAY_PTR(groups)[groupid];
rb_ary_push(group,cIGraph_get_vertex_object(self, i));
}
eigenvector_a = rb_ary_new();
for(i=0;i<igraph_vector_size(&eigenvector);i++){
rb_ary_push(eigenvector_a,rb_float_new(VECTOR(eigenvector)[i]));
}
res = rb_ary_new3(4,groups,split==0 ? Qfalse : Qtrue,
eigenvector_a,rb_float_new(eigenvalue));
igraph_vector_destroy(&membership_vec);
igraph_vector_destroy(&eigenvector);
return res;
}
int main() {
float dist[8][8] = {
{0.00, 4.69, 6.79, 3.50, 3.11, 4.46, 5.57, 3.00},
{4.69, 0.00, 2.10, 2.27, 2.65, 2.36, 1.99, 1.74},
{6.79, 2.10, 0.00, 3.78, 4.53, 2.83, 2.44, 3.79},
{3.50, 2.27, 3.78, 0.00, 1.98, 4.35, 2.07, 0.53},
{3.11, 2.65, 4.53, 1.98, 0.00, 3.80, 3.31, 1.47},
{4.46, 2.36, 2.83, 4.35, 3.80, 0.00, 4.35, 3.82},
{5.57, 1.99, 2.44, 2.07, 3.31, 4.35, 0.00, 2.57},
{3.00, 1.74, 3.79, 0.53, 1.47, 3.82, 2.57, 0.00},
};
igraph_t g;
igraph_matrix_t coords, dist_mat;
igraph_real_t vc;
igraph_arpack_options_t options;
int i, j;
srand(time(0));
igraph_arpack_options_init(&options);
igraph_tree(&g, 10, 2, IGRAPH_TREE_UNDIRECTED);
igraph_matrix_init(&coords, 0, 0);
igraph_layout_mds(&g, &coords, 0, 2, &options);
if (MATRIX(coords, 0, 0) > 0) {
for (i = 0; i < igraph_matrix_nrow(&coords); i++)
MATRIX(coords, i, 0) *= -1;
}
if (MATRIX(coords, 0, 1) < 0) {
for (i = 0; i < igraph_matrix_nrow(&coords); i++)
MATRIX(coords, i, 1) *= -1;
}
igraph_matrix_print(&coords);
igraph_matrix_destroy(&coords);
igraph_destroy(&g);
igraph_full(&g, 8, IGRAPH_UNDIRECTED, 0);
igraph_matrix_init(&coords, 8, 2);
igraph_matrix_init(&dist_mat, 8, 8);
for (i = 0; i < 8; i++)
for (j = 0; j < 2; j++)
MATRIX(coords, i, j) = rand() % 1000;
for (i = 0; i < 8; i++)
for (j = i+1; j < 8; j++) {
double dist_sq = 0.0;
dist_sq += sqr(MATRIX(coords, i, 0)-MATRIX(coords, j, 0));
dist_sq += sqr(MATRIX(coords, i, 1)-MATRIX(coords, j, 1));
MATRIX(dist_mat, i, j) = sqrt(dist_sq);
MATRIX(dist_mat, j, i) = sqrt(dist_sq);
}
igraph_layout_mds(&g, &coords, &dist_mat, 2, &options);
for (i = 0; i < 8; i++)
for (j = i+1; j < 8; j++) {
double dist_sq = 0.0;
dist_sq += sqr(MATRIX(coords, i, 0)-MATRIX(coords, j, 0));
dist_sq += sqr(MATRIX(coords, i, 1)-MATRIX(coords, j, 1));
if (fabs(sqrt(dist_sq) - MATRIX(dist_mat, i, j)) > 1e-2) {
printf("dist(%d,%d) should be %.4f, but it is %.4f\n",
i, j, MATRIX(dist_mat, i, j), sqrt(dist_sq));
return 1;
}
}
igraph_matrix_destroy(&dist_mat);
igraph_matrix_destroy(&coords);
igraph_destroy(&g);
return 0;
}
