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
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
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
|
/*
* Copyright 2008-2009 NVIDIA Corporation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <cusp/detail/config.h>
#include <cusp/array1d.h>
#include <cusp/exception.h>
#include <cusp/graph/breadth_first_search.h>
#include <thrust/copy.h>
#include <thrust/gather.h>
#include <thrust/iterator/counting_iterator.h>
namespace cusp
{
namespace graph
{
namespace detail
{
template<typename MatrixType, typename ArrayType>
typename MatrixType::index_type pseudo_peripheral_vertex(const MatrixType& G, ArrayType& levels, cusp::csr_format)
{
using namespace thrust::placeholders;
typedef typename MatrixType::index_type IndexType;
typedef typename MatrixType::memory_space MemorySpace;
IndexType delta = 0;
IndexType x = rand() % G.num_rows;
IndexType y;
ArrayType row_lengths(G.num_rows);
thrust::transform(G.row_offsets.begin() + 1, G.row_offsets.end(), G.row_offsets.begin(), row_lengths.begin(), thrust::minus<IndexType>());
while(1) {
cusp::graph::breadth_first_search<false>(G, x, levels);
typename ArrayType::iterator max_level_iter = thrust::max_element(levels.begin(), levels.end());
int max_level = *max_level_iter;
int max_count = thrust::count(levels.begin(), levels.end(), max_level);
if( max_count > 1 ) {
ArrayType max_level_vertices(max_count);
ArrayType max_level_valence(max_count);
thrust::copy_if(thrust::counting_iterator<IndexType>(0),
thrust::counting_iterator<IndexType>(G.num_rows),
levels.begin(),
max_level_vertices.begin(),
_1 == max_level);
thrust::gather(thrust::counting_iterator<IndexType>(0),
thrust::counting_iterator<IndexType>(max_count),
row_lengths.begin(),
max_level_valence.begin());
int min_valence_pos = thrust::min_element(max_level_valence.begin(), max_level_valence.end()) - max_level_valence.begin();
y = max_level_vertices[min_valence_pos];
}
else
{
y = max_level_iter - levels.begin();
}
if( levels[y] <= delta ) break;
x = y;
delta = levels[y];
}
return y;
}
//////////////////
// General Path //
//////////////////
template<typename MatrixType, typename ArrayType, typename Format>
typename MatrixType::index_type pseudo_peripheral_vertex(const MatrixType& G, ArrayType& levels, Format)
{
typedef typename MatrixType::index_type IndexType;
typedef typename MatrixType::value_type ValueType;
typedef typename MatrixType::memory_space MemorySpace;
// convert matrix to CSR format and compute on the host
cusp::csr_matrix<IndexType,ValueType,MemorySpace> G_csr(G);
return cusp::graph::pseudo_peripheral_vertex(G_csr, levels);
}
} // end namespace detail
/////////////////
// Entry Point //
/////////////////
template<typename MatrixType, typename ArrayType>
typename MatrixType::index_type pseudo_peripheral_vertex(const MatrixType& G, ArrayType& levels)
{
CUSP_PROFILE_SCOPED();
if(G.num_rows != G.num_cols)
throw cusp::invalid_input_exception("matrix must be square");
return cusp::graph::detail::pseudo_peripheral_vertex(G, levels, typename MatrixType::format());
}
template<typename MatrixType>
typename MatrixType::index_type pseudo_peripheral_vertex(const MatrixType& G)
{
typedef typename MatrixType::index_type IndexType;
typedef typename MatrixType::memory_space MemorySpace;
cusp::array1d<IndexType,MemorySpace> levels(G.num_rows);
return cusp::graph::pseudo_peripheral_vertex(G, levels);
}
} // end namespace graph
} // end namespace cusp
|
