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Several DSFMap variants

release/4.3a0
Frank Dellaert 2013-10-27 02:18:42 +00:00
parent f2941ce3b5
commit f4b7ab54b0
3 changed files with 271 additions and 56 deletions
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215
gtsam_unstable/base/DSFMap.h
View File

@ -18,10 +18,10 @@
#pragma once
#include <boost/foreach.hpp>
#include <map>
#include <set>
#include <boost/foreach.hpp>
#include <iostream>
namespace gtsam {
@ -33,6 +33,8 @@ namespace gtsam {
template<class KEY>
class DSFMap {
protected:
/// We store the forest in an STL map
typedef std::map<KEY, KEY> Map;
typedef std::set<KEY> Set;
@ -41,13 +43,14 @@ class DSFMap {
public:
/// constructor
DSFMap() {}
DSFMap() {
}
/// find the label of the set in which {key} lives
KEY find(const KEY& key) const {
typename Map::const_iterator it = parent_.find(key);
// if key does not exist, create and return itself
if (it==parent_.end()) {
if (it == parent_.end()) {
parent_[key] = key;
return key;
} else {
@ -75,4 +78,208 @@ public:
};
/**
* Disjoint set forest using an STL map data structure underneath
* Uses rank compression but not union by rank :-(
* @addtogroup base
*/
template<class KEY>
class DSFMapIt {
protected:
/// We store the forest in an STL map, but parents are done with pointers
struct Entry {
typedef std::map<KEY, Entry> Map;
typename Map::iterator parent_;
size_t rank_;
Entry() :
rank_(0) {
}
void makeRoot(const typename Map::iterator& it) {
parent_ = it;
}
};
mutable typename Entry::Map entries_;
/// find the initial Entry
typename Entry::Map::iterator find__(const KEY& key) const {
typename Entry::Map::iterator it = entries_.find(key);
// if key does not exist, create and return itself
if (it == entries_.end()) {
it = entries_.insert(it, std::make_pair(key, Entry()));
it->second.makeRoot(it);
}
return it;
}
/// find the root Entry
typename Entry::Map::iterator find_(const KEY& key) const {
typename Entry::Map::iterator initial = find__(key);
// follow parent pointers until we reach set representative
typename Entry::Map::iterator parent = initial->second.parent_;
while (parent->second.parent_ != parent)
parent = parent->second.parent_; // not yet, recurse!
//initial.parent_ = parent; // path compression
return parent;
}
public:
/// constructor
DSFMapIt() {
}
/// find the representative KEY for the set in which key lives
KEY find(const KEY& key) const {
typename Entry::Map::iterator root = find_(key);
return root->first;
}
/// Merge two sets
void merge(const KEY& x, const KEY& y) {
// straight from http://en.wikipedia.org/wiki/Disjoint-set_data_structure
typename Entry::Map::iterator xRoot = find_(x);
typename Entry::Map::iterator yRoot = find_(y);
if (xRoot == yRoot)
return;
// Merge sets
size_t xRootRank = xRoot->second.rank_, yRootRank = yRoot->second.rank_;
if (xRootRank < yRootRank)
xRoot->second.parent_ = yRoot;
else if (xRootRank > yRootRank)
yRoot->second.parent_ = xRoot;
else {
yRoot->second.parent_ = xRoot;
xRoot->second.rank_ = xRootRank + 1;
}
}
};
/**
* Disjoint set forest using an STL map data structure underneath
* Uses rank compression but not union by rank :-(
* @addtogroup base
*/
template<class KEY>
class DSFMap2 {
protected:
/// We store the forest in an STL map, but parents are done with pointers
struct Entry {
KEY key_;
size_t rank_;
Entry* parent_;
Entry(KEY key) :
key_(key), rank_(0), parent_(0) {
}
void makeRoot() {
parent_ = this;
}
};
typedef std::map<KEY, Entry> Map;
mutable Map entries_;
/// find the initial Entry
Entry& find__(const KEY& key) const {
typename Map::iterator it = entries_.find(key);
// if key does not exist, create and return itself
if (it == entries_.end()) {
it = entries_.insert(it, std::make_pair(key, Entry(key)));
it->second.makeRoot();
}
return it->second;
}
/// find the root Entry
Entry* find_(const KEY& key) const {
Entry& initial = find__(key);
// follow parent pointers until we reach set representative
Entry* parent = initial.parent_;
while (parent->parent_ != parent)
parent = parent->parent_; // not yet, recurse!
initial.parent_ = parent; // path compression
return parent;
}
public:
/// constructor
DSFMap2() {
}
/// find the representative KEY for the set in which key lives
KEY find(const KEY& key) const {
Entry* root = find_(key);
return root->key_;
}
/// Merge two sets
void merge(const KEY& x, const KEY& y) {
// straight from http://en.wikipedia.org/wiki/Disjoint-set_data_structure
Entry* xRoot = find_(x);
Entry* yRoot = find_(y);
if (xRoot == yRoot)
return;
// Merge sets
if (xRoot->rank_ < yRoot->rank_)
xRoot->parent_ = yRoot;
else if (xRoot->rank_ > yRoot->rank_)
yRoot->parent_ = xRoot;
else {
yRoot->parent_ = xRoot;
xRoot->rank_ = xRoot->rank_ + 1;
}
}
};
/**
* DSFMap version that uses union by rank :-)
* @addtogroup base
*/
template<class KEY>
class DSFMap3: public DSFMap<KEY> {
/// We store rank in an STL map as well
typedef std::map<KEY, size_t> Ranks;
mutable Ranks rank_;
size_t rank(const KEY& i) const {
typename Ranks::const_iterator it = rank_.find(i);
return it == rank_.end() ? 0 : it->second;
}
public:
/// constructor
DSFMap3() {
}
/// Merge two sets
void merge(const KEY& x, const KEY& y) {
// straight from http://en.wikipedia.org/wiki/Disjoint-set_data_structure
KEY xRoot = this->find(x);
KEY yRoot = this->find(y);
if (xRoot == yRoot)
return;
// Merge sets
size_t xRootRank = rank(xRoot), yRootRank = rank(yRoot);
if (xRootRank < yRootRank)
this->parent_[xRoot] = yRoot;
else if (xRootRank > yRootRank)
this->parent_[yRoot] = xRoot;
else {
this->parent_[yRoot] = xRoot;
this->rank_[xRoot] = xRootRank + 1;
}
}
};
}

34
gtsam_unstable/base/tests/testDSFMap.cpp
View File

@ -22,9 +22,9 @@
#include <boost/assign/std/list.hpp>
#include <boost/assign/std/set.hpp>
using namespace boost::assign;
//
#include <CppUnitLite/TestHarness.h>
//
#include <iostream>
using namespace std;
@ -32,7 +32,7 @@ using namespace gtsam;
/* ************************************************************************* */
TEST(DSFMap, find) {
DSFMap<size_t> dsf;
DSFMapIt<size_t> dsf;
EXPECT(dsf.find(0)==0);
EXPECT(dsf.find(2)==2);
EXPECT(dsf.find(0)==0);
@ -42,20 +42,21 @@ TEST(DSFMap, find) {
/* ************************************************************************* */
TEST(DSFMap, merge) {
DSFMap<size_t> dsf;
DSFMapIt<size_t> dsf;
dsf.merge(0,2);
EXPECT(dsf.find(0) == dsf.find(2));
}
/* ************************************************************************* */
TEST(DSFMap, merge2) {
DSFMap<size_t> dsf;
DSFMapIt<size_t> dsf;
dsf.merge(2,0);
EXPECT(dsf.find(0) == dsf.find(2));
}
/* ************************************************************************* */
TEST(DSFMap, merge3) {
DSFMap<size_t> dsf;
DSFMapIt<size_t> dsf;
dsf.merge(0,1);
dsf.merge(1,2);
EXPECT(dsf.find(0) == dsf.find(2));
@ -70,16 +71,14 @@ TEST(DSFMap, mergePairwiseMatches) {
matches += Match(1,2), Match(2,3), Match(4,5), Match(4,6);
// Merge matches
DSFMap<size_t> dsf;
DSFMapIt<size_t> dsf;
BOOST_FOREACH(const Match& m, matches)
dsf.merge(m.first,m.second);
// Each point is now associated with a set, represented by one of its members
size_t rep1 = 1, rep2 = 4;
EXPECT_LONGS_EQUAL(rep1,dsf.find(1));
size_t rep1 = dsf.find(1), rep2 = dsf.find(4);
EXPECT_LONGS_EQUAL(rep1,dsf.find(2));
EXPECT_LONGS_EQUAL(rep1,dsf.find(3));
EXPECT_LONGS_EQUAL(rep2,dsf.find(4));
EXPECT_LONGS_EQUAL(rep2,dsf.find(5));
EXPECT_LONGS_EQUAL(rep2,dsf.find(6));
}
@ -102,19 +101,17 @@ TEST(DSFMap, mergePairwiseMatches2) {
matches += Match(m11,m22), Match(m12,m23), Match(m14,m25), Match(m14,m26);
// Merge matches
DSFMap<Measurement> dsf;
DSFMapIt<Measurement> dsf;
BOOST_FOREACH(const Match& m, matches)
dsf.merge(m.first,m.second);
// Check that sets are merged correctly
EXPECT(dsf.find(m11)==m11);
EXPECT(dsf.find(m12)==m12);
EXPECT(dsf.find(m14)==m14);
EXPECT(dsf.find(m22)==m11);
EXPECT(dsf.find(m23)==m12);
EXPECT(dsf.find(m25)==m14);
EXPECT(dsf.find(m26)==m14);
EXPECT(dsf.find(m22)==dsf.find(m11));
EXPECT(dsf.find(m23)==dsf.find(m12));
EXPECT(dsf.find(m25)==dsf.find(m14));
EXPECT(dsf.find(m26)==dsf.find(m14));
}
/* ************************************************************************* */
TEST(DSFMap, sets){
// Create some "matches"
@ -143,6 +140,7 @@ TEST(DSFMap, sets){
EXPECT(s1 == sets[1]);
EXPECT(s2 == sets[4]);
}
/* ************************************************************************* */
int main() { TestResult tr; return TestRegistry::runAllTests(tr);}
/* ************************************************************************* */

14
gtsam_unstable/base/tests/timeDSFvariants.cpp
View File

@ -45,7 +45,7 @@ int main(int argc, char* argv[]) {
// loop over number of images
vector<size_t> ms;
ms += 10, 20, 30, 40, 50, 100, 200, 300, 400, 500;
ms += 10, 20, 30, 40, 50, 100, 200, 300, 400, 500, 1000;
BOOST_FOREACH(size_t m,ms) {
// We use volatile here to make these appear to the optimizing compiler as
// if their values are only known at run-time.
@ -82,7 +82,7 @@ int main(int argc, char* argv[]) {
{
// DSFMap version
timer tim;
DSFMap<size_t> dsf;
DSFMapIt<size_t> dsf;
BOOST_FOREACH(const Match& m, matches)
dsf.merge(m.first, m.second);
os << tim.elapsed() << ",";
@ -90,6 +90,16 @@ int main(int argc, char* argv[]) {
}
{
// DSFMap2 version
timer tim;
DSFMap2<size_t> dsf;
BOOST_FOREACH(const Match& m, matches)
dsf.merge(m.first, m.second);
os << tim.elapsed() << endl;
cout << format("DSFMap: %1% s") % tim.elapsed() << endl;
}
if (false) {
// DSF version, functional
timer tim;
DSF<size_t> dsf;