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/* Copyright (c) 1997-2024
Ewgenij Gawrilow, Michael Joswig, and the polymake team
Technische Universität Berlin, Germany
https://polymake.org
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, or (at your option) any
later version: http://www.gnu.org/licenses/gpl.txt.
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.
--------------------------------------------------------------------------------
*/
#pragma once
namespace polymake { namespace topaz {
//the following takes non-redundant, non-including faces and adjusts the numbering,
//returning a map from new indices to old ones. used in connection with boundary constructions.
struct ind2map_consumer {
mutable Array<Int> map;
mutable Int n_verts = 0;
ind2map_consumer(Int n)
: map(n) {};
void operator() (const Int& old_index, Int& new_index) const
{
map[new_index] = old_index;
n_verts = std::max(n_verts, new_index+1);
}
Array<Int> give_map()
{
return Array<Int>(n_verts, map.begin());
}
};
inline
std::pair<Array<Set<Int>>, Array<Int>>
squeeze_faces(IncidenceMatrix<> faces)
{
auto c = ind2map_consumer(faces.cols());
faces.squeeze_cols(c);
return std::make_pair(Array<Set<Int>>(rows(faces)), c.give_map());
}
} }
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
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