cyclus::GreedySolver Class Reference

Detailed Description

The GreedySolver provides the implementation for a "greedy" solution to a resource exchange graph.

Given an ExchangeGraph, the greedy solver will march through each RequestGroup in the graph, matching request nodes "greedily" with supply nodes. Each request node will attempt to be supplied by supplier arcs as long as those supplier arcs have some excess capacity. The possible suppliers will be ordered by descending preference. The algorithm terminates when one of the following conditions is met: 1) All RequestGroups are satisfied 2) All SupplySets are at capacity

Warning

the GreedySolver is responsible for deleting is conditioner!

Definition at line 64 of file greedy_solver.h.

#include <greedy_solver.h>

Inheritance diagram for cyclus::GreedySolver:

Public Member Functions
double	Capacity (const Arc &a)
double	Capacity (const Arc &a, double u_curr_qty, double v_curr_qty)
void	Condition ()
void	Init ()
virtual	~GreedySolver ()
	GreedySolver ()
	GreedySolver (bool exclusive_orders)
	GreedySolver (GreedyPreconditioner *c)
	GreedySolver (bool exclusive_orders, GreedyPreconditioner *c)
double	Capacity (ExchangeNode::Ptr n, const Arc &a, bool min_cap, double curr_qty)
double	Capacity (ExchangeNode::Ptr n, const Arc &a, bool min_cap)
double	Capacity (ExchangeNode::Ptr n, const Arc &a, double curr_qty)
double	Capacity (ExchangeNode::Ptr n, const Arc &a)
Public Member Functions inherited from cyclus::ExchangeSolver
double	ArcCost (const Arc &a)
	ExchangeSolver (bool exclusive_orders=kDefaultExclusive)
ExchangeGraph *	graph () const
void	graph (ExchangeGraph *graph)
double	Solve (ExchangeGraph *graph=NULL)
void	verbose ()
virtual	~ExchangeSolver ()
void	sim_ctx (Context *c)
Context *	sim_ctx ()
double	PseudoCost ()
double	PseudoCost (double cost_factor)
double	PseudoCostByCap (double cost_factor)
double	PseudoCostByPref (double cost_factor)

Protected Member Functions
virtual double	SolveGraph ()

Additional Inherited Members
Static Public Member Functions inherited from cyclus::ExchangeSolver
static double	Cost (const Arc &a, bool exclusive_orders=kDefaultExclusive)
Static Public Attributes inherited from cyclus::ExchangeSolver
static const bool	kDefaultExclusive = true
Protected Attributes inherited from cyclus::ExchangeSolver
bool	exclusive_orders_
ExchangeGraph *	graph_
Context *	sim_ctx_
bool	verbose_

Constructor & Destructor Documentation

GreedySolver() [1/4]

cyclus::GreedySolver::GreedySolver

(

)

GreedySolver constructor.

Parameters

exclusive_orders	a flag for enforcing integral, quantized orders
c	a conditioner to use before solving a graph instance

Warning

if a NULL pointer is passed as a conditioner argument, conditioning will NOT occur

Definition at line 32 of file greedy_solver.cc.

GreedySolver() [2/4]

cyclus::GreedySolver::GreedySolver ( bool exclusive_orders )

explicit

Definition at line 23 of file greedy_solver.cc.

GreedySolver() [3/4]

cyclus::GreedySolver::GreedySolver ( GreedyPreconditioner * c )

explicit

Definition at line 28 of file greedy_solver.cc.

GreedySolver() [4/4]

cyclus::GreedySolver::GreedySolver	(	bool	exclusive_orders,
		GreedyPreconditioner *	c )

Definition at line 19 of file greedy_solver.cc.

~GreedySolver()

cyclus::GreedySolver::~GreedySolver ( )

virtual

Definition at line 36 of file greedy_solver.cc.

Member Function Documentation

Capacity() [1/6]

double cyclus::GreedySolver::Capacity ( const Arc & a )

inline

Definition at line 102 of file greedy_solver.h.

Capacity() [2/6]

double cyclus::GreedySolver::Capacity	(	const Arc &	a,
		double	u_curr_qty,
		double	v_curr_qty )

the capacity of the arc

Exceptions

StateError

if either ExchangeNode does not have a ExchangeNodeGroup

Parameters

a	the arc
u_curr_qty	the current quantity assigned to the unode (if solving piecemeal)
v_curr_qty	the current quantity assigned to the vnode (if solving piecemeal)

Returns

The minimum of the unode and vnode's capacities

Definition at line 82 of file greedy_solver.cc.

Capacity() [3/6]

double cyclus::GreedySolver::Capacity ( ExchangeNode::Ptr n, const Arc & a )

inline

Definition at line 125 of file greedy_solver.h.

Capacity() [4/6]

double cyclus::GreedySolver::Capacity ( ExchangeNode::Ptr n, const Arc & a, bool min_cap )

inline

Definition at line 119 of file greedy_solver.h.

Capacity() [5/6]

double cyclus::GreedySolver::Capacity	(	ExchangeNode::Ptr	n,
		const Arc &	a,
		bool	min_cap,
		double	curr_qty )

the capacity of a node

Exceptions

StateError

if ExchangeNode does not have a ExchangeNodeGroup

Parameters

n	the node
min_cap	whether to use the minimum or maximum capacity value. In general, nodes that represent bids use the minimum (i.e., the capacities represents a less-than constraint) and nodes that represent requests use the maximum value (i.e., the capacities represents a greater-than constraint).
curr_qty	the currently allocated node quantity (if solving piecemeal)

Returns

The minimum of the node's nodegroup capacities / the node's unit capacities, or the ExchangeNode's remaining qty – whichever is smaller.

Definition at line 96 of file greedy_solver.cc.

Capacity() [6/6]

double cyclus::GreedySolver::Capacity ( ExchangeNode::Ptr n, const Arc & a, double curr_qty )

inline

Definition at line 122 of file greedy_solver.h.

Condition()

void cyclus::GreedySolver::Condition

(

)

Uses the provided (or a default) GreedyPreconditioner to condition the solver's ExchangeGraph so that RequestGroups are ordered by average preference and commodity weight.

Warning

this function is called during the Solve step and should most likely not be called independently thereof (except for testing)

Definition at line 41 of file greedy_solver.cc.

Init()

void cyclus::GreedySolver::Init

(

)

Initialize member values based on the given graph.

Definition at line 46 of file greedy_solver.cc.

SolveGraph()

double cyclus::GreedySolver::SolveGraph ( )

protectedvirtual

the GreedySolver solves an ExchangeGraph by iterating over each RequestGroup and matching requests with the minimum bids possible, starting from the beginning of the the respective request and bid containers.

Implements cyclus::ExchangeSolver.

Definition at line 62 of file greedy_solver.cc.

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The documentation for this class was generated from the following files:

• greedy_solver.h
• greedy_solver.cc