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Zoltan2_AlgRandom.hpp
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5// Zoltan2: A package of combinatorial algorithms for scientific computing
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45#ifndef _ZOLTAN2_ALGRANDOM_HPP_
46#define _ZOLTAN2_ALGRANDOM_HPP_
47
48#include <Zoltan2_Algorithm.hpp>
51
52
53namespace Zoltan2{
54
59
60template <typename Adapter>
61class AlgRandom : public Algorithm<Adapter>
62{
63 private:
64
65 const RCP<const typename Adapter::base_adapter_t> adapter;
66 const RCP<Teuchos::ParameterList> pl;
67 const RCP<const Teuchos::Comm<int> > comm;
68 const RCP<const Environment> env;
69
70 public:
71
72 typedef typename Adapter::lno_t lno_t;
73 typedef typename Adapter::gno_t gno_t;
74
76 const RCP<const typename Adapter::base_adapter_t> &adapter__,
77 const RCP<Teuchos::ParameterList> &pl__,
78 const RCP<const Teuchos::Comm<int> > &comm__,
79 const RCP<const Environment> &env__
80 ) : adapter(adapter__), pl(pl__), comm(comm__), env(env__)
81 {
82 }
83
84 int globalOrder(const RCP<GlobalOrderingSolution<gno_t> > &/* solution */)
85 {
86 throw std::logic_error("AlgRandom does not yet support global ordering.");
87 }
88
89 int localOrder(const RCP<LocalOrderingSolution<lno_t> > &solution)
90 {
91
92 int ierr= 0;
93
94 HELLO;
95
96 // This is the Fisher-Yates shuffle (aka Knuth shuffle).
97 // References:
98 // R.A. Fisher, F. Yates, (1948) [1938], Statistical tables for biological, agricultural and medical research (3rd ed.).
99 // R. Durstenfeld, "Algorithm 235: Random permutation", CACM, vol. 7, 1964.
100 // D.E. Knuth, "The Art of Computer Programming", volume 2, 1969.
101
102 // Start with the identity permutation.
103 modelFlag_t modelFlags;
104 const auto model = rcp(new IdentifierModel<Adapter>(adapter, env, comm, modelFlags));
105 const size_t n = model->getLocalNumIdentifiers();
106 lno_t *perm;
107 perm = (lno_t *) (solution->getPermutationRCP().getRawPtr());
108 if (perm){
109 for (size_t i=0; i<n; i++){
110 perm[i] = i;
111 }
112 }
113 else
114 // throw exception?
115 ierr = -1;
116
117 // Swap random pairs of indices in perm.
118 lno_t j, temp;
119 for (lno_t i=n-1; i>0; i--){
120 // Choose j randomly in [0,i]
121 j = rand() % (i+1);
122 // Swap (perm[i], perm[j])
123 temp = perm[i];
124 perm[i] = perm[j];
125 perm[j] = temp;
126 }
127
128 solution->setHavePerm(true);
129 return ierr;
130
131 }
132
133};
134}
135#endif
Defines the IdentifierModel interface.
Defines the OrderingSolution class.
#define HELLO
AlgRandom(const RCP< const typename Adapter::base_adapter_t > &adapter__, const RCP< Teuchos::ParameterList > &pl__, const RCP< const Teuchos::Comm< int > > &comm__, const RCP< const Environment > &env__)
int localOrder(const RCP< LocalOrderingSolution< lno_t > > &solution)
Ordering method.
int globalOrder(const RCP< GlobalOrderingSolution< gno_t > > &)
Ordering method.
Algorithm defines the base class for all algorithms.
IdentifierModel defines the interface for all identifier models.
Created by mbenlioglu on Aug 31, 2020.
std::bitset< NUM_MODEL_FLAGS > modelFlag_t