blob: 461a01e7637fd41a48bd704fcb5a30e40791adb3 (
plain)
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
|
/* This file is part of the Gudhi Library. The Gudhi library
* (Geometric Understanding in Higher Dimensions) is a generic C++
* library for computational topology.
*
* Author(s): Siargey Kachanovich
*
* Copyright (C) 2019 Inria
*
* Modification(s):
* - YYYY/MM Author: Description of the modification
*/
#ifndef PERMUTAHEDRAL_REPRESENTATION_FACE_FROM_INDICES_H_
#define PERMUTAHEDRAL_REPRESENTATION_FACE_FROM_INDICES_H_
namespace Gudhi {
namespace coxeter_triangulation {
/** \brief Computes the permutahedral representation of a face of a given simplex
* and a range of the vertex indices that compose the face.
*
* \tparam Permutahedral_representation has to be Permutahedral_representation
* \tparam Index_range is a range of unsigned integers taking values in 0,...,k,
* where k is the dimension of the simplex simplex.
*
* @param[in] simplex Input simplex.
* @param[in] indices Input range of indices.
*/
template <class Permutahedral_representation,
class Index_range>
Permutahedral_representation face_from_indices(const Permutahedral_representation& simplex,
const Index_range& indices) {
using range_index = typename Index_range::value_type;
using Ordered_set_partition = typename Permutahedral_representation::OrderedSetPartition;
using Part = typename Ordered_set_partition::value_type;
using part_index = typename Part::value_type;
Permutahedral_representation value;
std::size_t d = simplex.vertex().size();
value.vertex() = simplex.vertex();
std::size_t k = indices.size()-1;
value.partition().resize(k+1);
std::size_t l = simplex.partition().size()-1;
for (std::size_t h = 1; h < k+1; h++)
for (range_index i = indices[h-1]; i < indices[h]; i++)
for (part_index j: simplex.partition()[i])
value.partition()[h-1].push_back(j);
for (range_index i = indices[k]; i < l+1; i++)
for (part_index j: simplex.partition()[i])
value.partition()[k].push_back(j);
for (range_index i = 0; i < indices[0]; i++)
for (part_index j: simplex.partition()[i]) {
if (j != d)
value.vertex()[j]++;
else
for (std::size_t l = 0; l < d; l++)
value.vertex()[l]--;
value.partition()[k].push_back(j);
}
// sort the values in each part (probably not needed)
for (auto& part: value.partition())
std::sort(part.begin(), part.end());
return value;
}
} // namespace coxeter_triangulation
} // namespace Gudhi
#endif
|
