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/* -*- mode: C -*- */
/*
IGraph R package.
Copyright (C) 2006-2012 Gabor Csardi <csardi.gabor@gmail.com>
334 Harvard street, Cambridge, MA 02139 USA
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 2 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, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#include "igraph_constructors.h"
#include "atlas-edges.h"
#include "config.h"
/**
* \function igraph_atlas
* \brief Create a small graph from the \quote Graph Atlas \endquote.
*
* </para><para>
* The number of the graph is given as a parameter.
* The graphs are listed: \olist
* \oli in increasing order of number of nodes;
* \oli for a fixed number of nodes, in increasing order of the
* number of edges;
* \oli for fixed numbers of nodes and edges, in increasing
* order of the degree sequence, for example 111223 < 112222;
* \oli for fixed degree sequence, in increasing number of
* automorphisms.
* \endolist
*
* </para><para>
* The data was converted from the NetworkX software package,
* see http://networkx.github.io .
*
* </para><para>
* See \emb An Atlas of Graphs \eme by Ronald C. Read and Robin J. Wilson,
* Oxford University Press, 1998.
*
* \param graph Pointer to an uninitialized graph object.
* \param number The number of the graph to generate.
*
* Added in version 0.2.</para><para>
*
* Time complexity: O(|V|+|E|), the number of vertices plus the number of
* edges.
*
* \example examples/simple/igraph_atlas.c
*/
int igraph_atlas(igraph_t *graph, int number) {
igraph_integer_t pos, n, e;
igraph_vector_t v=IGRAPH_VECTOR_NULL;
if (number < 0 ||
number >= (int) (sizeof(igraph_i_atlas_edges_pos)/sizeof(long int))) {
IGRAPH_ERROR("No such graph in atlas", IGRAPH_EINVAL);
}
pos=(igraph_integer_t) igraph_i_atlas_edges_pos[number];
n=(igraph_integer_t) igraph_i_atlas_edges[pos];
e=(igraph_integer_t) igraph_i_atlas_edges[pos+1];
IGRAPH_CHECK(igraph_create(graph,
igraph_vector_view(&v,igraph_i_atlas_edges+pos+2,
e*2),
n, IGRAPH_UNDIRECTED));
return 0;
}
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