[Lemon-commits] kpeter: r3466 - lemon/trunk/lemon
Lemon SVN
svn at lemon.cs.elte.hu
Thu Feb 28 03:57:37 CET 2008
Author: kpeter
Date: Thu Feb 28 03:57:36 2008
New Revision: 3466
Modified:
lemon/trunk/lemon/min_mean_cycle.h
Log:
Small fixes and doc improvements in MinMeanCycle.
Modified: lemon/trunk/lemon/min_mean_cycle.h
==============================================================================
--- lemon/trunk/lemon/min_mean_cycle.h (original)
+++ lemon/trunk/lemon/min_mean_cycle.h Thu Feb 28 03:57:36 2008
@@ -26,9 +26,9 @@
#include <vector>
#include <lemon/graph_utils.h>
-#include <lemon/topology.h>
#include <lemon/path.h>
#include <lemon/tolerance.h>
+#include <lemon/topology.h>
namespace lemon {
@@ -41,8 +41,8 @@
/// \ref MinMeanCycle implements Howard's algorithm for finding a
/// minimum mean directed cycle.
///
- /// \param Graph The directed graph type the algorithm runs on.
- /// \param LengthMap The type of the length (cost) map.
+ /// \tparam Graph The directed graph type the algorithm runs on.
+ /// \tparam LengthMap The type of the length (cost) map.
///
/// \warning \c LengthMap::Value must be convertible to \c double.
///
@@ -57,28 +57,28 @@
typedef typename LengthMap::Value Length;
typedef Path<Graph> Path;
- protected:
-
- typename Graph::template NodeMap<bool> _reached;
- typename Graph::template NodeMap<double> _dist;
- typename Graph::template NodeMap<Edge> _policy;
+ private:
- /// The directed graph the algorithm runs on.
+ // The directed graph the algorithm runs on
const Graph &_graph;
- /// The length of the edges.
+ // The length of the edges
const LengthMap &_length;
- /// The total length of the found cycle.
+ // The total length of the found cycle
Length _cycle_length;
- /// The number of edges on the found cycle.
+ // The number of edges on the found cycle
int _cycle_size;
- /// The found cycle.
+ // The found cycle
Path *_cycle_path;
bool _local_path;
bool _cycle_found;
Node _cycle_node;
+ typename Graph::template NodeMap<bool> _reached;
+ typename Graph::template NodeMap<double> _dist;
+ typename Graph::template NodeMap<Edge> _policy;
+
typename Graph::template NodeMap<int> _component;
int _component_num;
@@ -96,17 +96,204 @@
/// \param length The length (cost) of the edges.
MinMeanCycle( const Graph &graph,
const LengthMap &length ) :
- _graph(graph), _length(length), _dist(graph), _reached(graph),
- _policy(graph), _component(graph), _cycle_length(0),
- _cycle_size(-1), _cycle_path(NULL), _local_path(false)
- { }
+ _graph(graph), _length(length), _cycle_length(0), _cycle_size(-1),
+ _cycle_path(NULL), _local_path(false), _reached(graph),
+ _dist(graph), _policy(graph), _component(graph)
+ {}
/// The destructor of the class.
~MinMeanCycle() {
if (_local_path) delete _cycle_path;
}
- protected:
+ /// \brief Sets the \ref Path "path" structure for storing the found
+ /// cycle.
+ ///
+ /// Sets an external \ref Path "path" structure for storing the
+ /// found cycle.
+ ///
+ /// If you don't call this function before calling \ref run() or
+ /// \ref init(), it will allocate a local \ref Path "path"
+ /// structure.
+ /// The destuctor deallocates this automatically allocated map,
+ /// of course.
+ ///
+ /// \note The algorithm calls only the \ref lemon::Path::addBack()
+ /// "addBack()" function of the given \ref Path "path" structure.
+ ///
+ /// \return <tt>(*this)</tt>
+ ///
+ /// \sa cycle()
+ MinMeanCycle& cyclePath(Path &path) {
+ if (_local_path) {
+ delete _cycle_path;
+ _local_path = false;
+ }
+ _cycle_path = &path;
+ return *this;
+ }
+
+ /// \name Execution control
+ /// The simplest way to execute the algorithm is to call run().
+ /// \n
+ /// If you only need the minimum mean value, you may call init()
+ /// and findMinMean().
+ /// \n
+ /// If you would like to run the algorithm again (e.g. the
+ /// underlaying graph and/or the edge costs were modified), you may
+ /// not create a new instance of the class, rather call reset(),
+ /// findMinMean(), and findCycle() instead.
+
+ /// @{
+
+ /// \brief Runs the algorithm.
+ ///
+ /// Runs the algorithm.
+ ///
+ /// \return Returns \c true if a directed cycle exists in the graph.
+ ///
+ /// \note Apart from the return value, <tt>mmc.run()</tt> is just a
+ /// shortcut of the following code.
+ /// \code
+ /// mmc.init();
+ /// mmc.findMinMean();
+ /// mmc.findCycle();
+ /// \endcode
+ bool run() {
+ init();
+ return findMinMean() && findCycle();
+ }
+
+ /// \brief Initializes the internal data structures.
+ ///
+ /// Initializes the internal data structures.
+ ///
+ /// \sa reset()
+ void init() {
+ _tolerance.epsilon(1e-6);
+ if (!_cycle_path) {
+ _local_path = true;
+ _cycle_path = new Path;
+ }
+ _cycle_found = false;
+ _component_num = stronglyConnectedComponents(_graph, _component);
+ }
+
+ /// \brief Resets the internal data structures.
+ ///
+ /// Resets the internal data structures so that \ref findMinMean()
+ /// and \ref findCycle() can be called again (e.g. when the
+ /// underlaying graph has been modified).
+ ///
+ /// \sa init()
+ void reset() {
+ if (_cycle_path) _cycle_path->clear();
+ _cycle_found = false;
+ _component_num = stronglyConnectedComponents(_graph, _component);
+ }
+
+ /// \brief Finds the minimum cycle mean length in the graph.
+ ///
+ /// Computes all the required data and finds the minimum cycle mean
+ /// length in the graph.
+ ///
+ /// \return Returns \c true if a directed cycle exists in the graph.
+ ///
+ /// \pre \ref init() must be called before using this function.
+ bool findMinMean() {
+ // Finding the minimum mean cycle in the components
+ for (int comp = 0; comp < _component_num; ++comp) {
+ if (!initCurrentComponent(comp)) continue;
+ while (true) {
+ if (!findPolicyCycles()) break;
+ contractPolicyGraph(comp);
+ if (!computeNodeDistances(comp)) break;
+ }
+ }
+ return _cycle_found;
+ }
+
+ /// \brief Finds a critical (minimum mean) directed cycle.
+ ///
+ /// Finds a critical (minimum mean) directed cycle using the data
+ /// computed in the \ref findMinMean() function.
+ ///
+ /// \return Returns \c true if a directed cycle exists in the graph.
+ ///
+ /// \pre \ref init() and \ref findMinMean() must be called before
+ /// using this function.
+ bool findCycle() {
+ if (!_cycle_found) return false;
+ _cycle_path->addBack(_policy[_cycle_node]);
+ for ( Node v = _cycle_node;
+ (v = _graph.target(_policy[v])) != _cycle_node; ) {
+ _cycle_path->addBack(_policy[v]);
+ }
+ return true;
+ }
+
+ /// @}
+
+ /// \name Query Functions
+ /// The result of the algorithm can be obtained using these
+ /// functions.
+ /// \n run() must be called before using them.
+
+ /// @{
+
+ /// \brief Returns the total length of the found cycle.
+ ///
+ /// Returns the total length of the found cycle.
+ ///
+ /// \pre \ref run() or \ref findMinMean() must be called before
+ /// using this function.
+ Length cycleLength() const {
+ return _cycle_length;
+ }
+
+ /// \brief Returns the number of edges on the found cycle.
+ ///
+ /// Returns the number of edges on the found cycle.
+ ///
+ /// \pre \ref run() or \ref findMinMean() must be called before
+ /// using this function.
+ int cycleEdgeNum() const {
+ return _cycle_size;
+ }
+
+ /// \brief Returns the mean length of the found cycle.
+ ///
+ /// Returns the mean length of the found cycle.
+ ///
+ /// \pre \ref run() or \ref findMinMean() must be called before
+ /// using this function.
+ ///
+ /// \note <tt>mmc.cycleMean()</tt> is just a shortcut of the
+ /// following code.
+ /// \code
+ /// return double(mmc.cycleLength()) / mmc.cycleEdgeNum();
+ /// \endcode
+ double cycleMean() const {
+ return double(_cycle_length) / _cycle_size;
+ }
+
+ /// \brief Returns a const reference to the \ref Path "path"
+ /// structure storing the found cycle.
+ ///
+ /// Returns a const reference to the \ref Path "path"
+ /// structure storing the found cycle.
+ ///
+ /// \pre \ref run() or \ref findCycle() must be called before using
+ /// this function.
+ ///
+ /// \sa cyclePath()
+ const Path& cycle() const {
+ return *_cycle_path;
+ }
+
+ ///@}
+
+ private:
// Initializes the internal data structures for the current strongly
// connected component and creating the policy graph.
@@ -127,12 +314,12 @@
_edges.push_back(e);
}
// Initializing _reached, _dist, _policy maps
- for (int i = 0; i < _nodes.size(); ++i) {
+ for (int i = 0; i < int(_nodes.size()); ++i) {
_reached[_nodes[i]] = false;
_policy[_nodes[i]] = INVALID;
}
Node u; Edge e;
- for (int j = 0; j < _edges.size(); ++j) {
+ for (int j = 0; j < int(_edges.size()); ++j) {
e = _edges[j];
u = _graph.source(e);
if (!_reached[u] || _length[e] < _dist[u]) {
@@ -148,15 +335,15 @@
// Sets _cycle_found to true if a cycle is found and sets
// _cycle_length, _cycle_size, _cycle_node to represent the minimum
// mean cycle in the policy graph.
- bool findPolicyCycles(int comp) {
+ bool findPolicyCycles() {
typename Graph::template NodeMap<int> level(_graph, -1);
- _cycle_found = false;
+ bool curr_cycle_found = false;
Length clength;
int csize;
int path_cnt = 0;
Node u, v;
// Searching for cycles
- for (int i = 0; i < _nodes.size(); ++i) {
+ for (int i = 0; i < int(_nodes.size()); ++i) {
if (level[_nodes[i]] < 0) {
u = _nodes[i];
level[u] = path_cnt;
@@ -164,6 +351,7 @@
level[u] = path_cnt;
if (level[u] == path_cnt) {
// A cycle is found
+ curr_cycle_found = true;
clength = _length[_policy[u]];
csize = 1;
for (v = u; (v = _graph.target(_policy[v])) != u; ) {
@@ -181,7 +369,7 @@
++path_cnt;
}
}
- return _cycle_found;
+ return curr_cycle_found;
}
// Contracts the policy graph to be connected by cutting all cycles
@@ -207,10 +395,10 @@
// Connecting all other nodes to this component using
// reverse BFS search
queue.clear();
- for (int i = 0; i < _nodes.size(); ++i)
+ for (int i = 0; i < int(_nodes.size()); ++i)
if (found[_nodes[i]]) queue.push_back(_nodes[i]);
int found_cnt = queue.size();
- while (found_cnt < _nodes.size() && !queue.empty()) {
+ while (found_cnt < int(_nodes.size()) && !queue.empty()) {
v = queue.front(); queue.pop_front();
for (InEdgeIt e(_graph, v); e != INVALID; ++e) {
u = _graph.source(e);
@@ -228,11 +416,12 @@
// policy graph if the node distances can be improved.
bool computeNodeDistances(int comp) {
// Computing node distances using reverse BFS search
- double cycle_mean = (double)_cycle_length / _cycle_size;
+ double cycle_mean = double(_cycle_length) / _cycle_size;
typename Graph::template NodeMap<int> found(_graph, false);
std::deque<Node> queue;
queue.push_back(_cycle_node);
found[_cycle_node] = true;
+ _dist[_cycle_node] = 0;
Node u, v;
while (!queue.empty()) {
v = queue.front(); queue.pop_front();
@@ -247,7 +436,7 @@
}
// Improving node distances
bool improved = false;
- for (int j = 0; j < _edges.size(); ++j) {
+ for (int j = 0; j < int(_edges.size()); ++j) {
Edge e = _edges[j];
u = _graph.source(e); v = _graph.target(e);
double delta = _dist[v] + _length[e] - cycle_mean;
@@ -260,170 +449,6 @@
return improved;
}
- public:
-
- /// \brief Runs the algorithm.
- ///
- /// Runs the algorithm.
- ///
- /// \return Returns \c true if a directed cycle exists in the graph.
- ///
- /// \note Apart from the return value, <tt>mmc.run()</tt> is just a
- /// shortcut of the following code.
- /// \code
- /// mmc.init();
- /// mmc.findMinMean();
- /// mmc.findCycle();
- /// \endcode
- bool run() {
- init();
- return findMinMean() && findCycle();
- }
-
- /// \brief Initializes the internal data structures.
- ///
- /// Initializes the internal data structures.
- ///
- /// \sa reset()
- void init() {
- _tolerance.epsilon(1e-8);
- if (!_cycle_path) {
- _local_path = true;
- _cycle_path = new Path;
- }
- _cycle_found = false;
- _component_num = stronglyConnectedComponents(_graph, _component);
- }
-
- /// \brief Resets the internal data structures.
- ///
- /// Resets the internal data structures so that \ref findMinMean()
- /// and \ref findCycle() can be called again (e.g. when the
- /// underlaying graph has been modified).
- ///
- /// \sa init()
- void reset() {
- if (_cycle_path) _cycle_path->clear();
- _cycle_found = false;
- _component_num = stronglyConnectedComponents(_graph, _component);
- }
-
- /// \brief Finds the minimum cycle mean length in the graph.
- ///
- /// Computes all the required data and finds the minimum cycle mean
- /// length in the graph.
- ///
- /// \return Returns \c true if a directed cycle exists in the graph.
- ///
- /// \pre \ref init() must be called before using this function.
- bool findMinMean() {
- // Finding the minimum mean cycle in the components
- for (int comp = 0; comp < _component_num; ++comp) {
- if (!initCurrentComponent(comp)) continue;
- while (true) {
- if (!findPolicyCycles(comp)) return false;
- contractPolicyGraph(comp);
- if (!computeNodeDistances(comp)) return true;
- }
- }
- }
-
- /// \brief Finds a critical (minimum mean) directed cycle.
- ///
- /// Finds a critical (minimum mean) directed cycle using the data
- /// computed in the \ref findMinMean() function.
- ///
- /// \return Returns \c true if a directed cycle exists in the graph.
- ///
- /// \pre \ref init() and \ref findMinMean() must be called before
- /// using this function.
- bool findCycle() {
- if (!_cycle_found) return false;
- _cycle_path->addBack(_policy[_cycle_node]);
- for ( Node v = _cycle_node;
- (v = _graph.target(_policy[v])) != _cycle_node; ) {
- _cycle_path->addBack(_policy[v]);
- }
- return true;
- }
-
- /// \brief Returns the total length of the found cycle.
- ///
- /// Returns the total length of the found cycle.
- ///
- /// \pre \ref run() or \ref findMinMean() must be called before
- /// using this function.
- Length cycleLength() const {
- return _cycle_length;
- }
-
- /// \brief Returns the number of edges on the found cycle.
- ///
- /// Returns the number of edges on the found cycle.
- ///
- /// \pre \ref run() or \ref findMinMean() must be called before
- /// using this function.
- int cycleEdgeNum() const {
- return _cycle_size;
- }
-
- /// \brief Returns the mean length of the found cycle.
- ///
- /// Returns the mean length of the found cycle.
- ///
- /// \pre \ref run() or \ref findMinMean() must be called before
- /// using this function.
- ///
- /// \note <tt>mmc.cycleMean()</tt> is just a shortcut of the
- /// following code.
- /// \code
- /// return double(mmc.cycleLength()) / mmc.cycleEdgeNum();
- /// \endcode
- double cycleMean() const {
- return (double)_cycle_length / _cycle_size;
- }
-
- /// \brief Returns a const reference to the \ref Path "path"
- /// structure storing the found cycle.
- ///
- /// Returns a const reference to the \ref Path "path"
- /// structure storing the found cycle.
- ///
- /// \pre \ref run() or \ref findCycle() must be called before using
- /// this function.
- ///
- /// \sa cyclePath()
- const Path& cycle() const {
- return *_cycle_path;
- }
-
- /// \brief Sets the \ref Path "path" structure for storing the found
- /// cycle.
- ///
- /// Sets an external \ref Path "path" structure for storing the
- /// found cycle.
- ///
- /// If you don't call this function before calling \ref run() or
- /// \ref init(), it will allocate a local \ref Path "path"
- /// structure.
- /// The destuctor deallocates this automatically allocated map,
- /// of course.
- ///
- /// \note The algorithm calls only the \ref lemon::Path::addBack()
- /// "addBack()" function of the given \ref Path "path" structure.
- ///
- /// \return <tt>(*this)</tt>
- ///
- /// \sa cycle()
- MinMeanCycle& cyclePath(Path &path) {
- if (_local_path) {
- delete _cycle_path;
- _local_path = false;
- }
- _cycle_path = &path;
- return *this;
- }
-
}; //class MinMeanCycle
///@}
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