WeightedMove

The class WeightedMove is derived from Action and lets agents move in directions with weighted probabilities. This class uses an array assigning a value to each cell of the grid and forms a small array of probabilities corresponding to the neighbors of each cell.

Code:
WeightedMove.h
WeightedMove.cpp

Attributes:

ATTR_WEIGHTEDMOVE_NAME

“WeightedMove”

action name

ATTR_WEIGHTEDMOVE_PROB_NAME

“WeightedMove_prob”

move probability

Public Methods

constructor

WeightedMove(SPopulation<T> *pPop, SCellGrid *pCG, std::string sID, WELL512 **apWELL, double *adEnvWeights);
pPop

A pointer to the SPopulation object performing this action.

pCG

A pointer to the SCellGrid object on which the simulation runs.

sActionName

Name of this action.

sID

An ID for this action.

apWELL

A pointer to an array of WELL512 random number generators (one for each thread).

adEnvWeight

An array with cumulated preference a value for each cell of the grid and its neoighbors.

The array adEnvWeight serves as communication channel between WeightedMove and an other action, typically an Evaluator such as SingleEvaluator.

This array is actually an array of “subarrays”, each of which has a size one greater than the maximum number of neighbors of a cell, where each subarray corresponds to a cell, representing the cell itself and its neighborhood.. The 0-th field of the subarray holds the preference value of the cell itself, the i-th element is the sum of the previous value and the preference value if the (i-1)th neighbor

../../images/WeightedRand.png

An array of values is cumulated (e.g. as produced by SingleEvaluator, and used as a lookup table to create a weighted random number. In this example a uniform random number R between 0 and the highest number in the cumulated array is drawn, and the index of the smallest cumulated value greater than R is chosen. Here the random number 0.81 is less than the value at index 4, 0.95, so the chosen index is 4. Hence those indexes are selected with a probability proportional to the values in the original array.

destructor

virtual ~WeightedMove();

The destructor does nothing.

execute

virtual int execute(int iA, float fT);
iAgentIndex

Current agent’s index.

fT

Current simulation step.

This method is called for all agents (in parallel).
For each agent the weight values corresponding to the agents location and the neighboring cells are accumulated in an array to get a weighted random number for which cell to move to.

extractAttributesQDF

virtual int extractAttributesQDF(hid_t hSpeciesGroup);
hSpeciesGroup

HDF handle for the species group to read from.

This method reads the move probability from a QDF file.

writeAttributesQDF

virtual int writeAttributesQDF(hid_t hSpeciesGroup);
hSpeciesGroup

HDF handle for the species group to write to.

This method writes the move probability to the specified group in a QDF file.

tryGetAttributes

virtual int tryGetAttributes(const ModuleComplex *pMC);
pMC

A ModuleComplex object.

Extracts the move probability from the ModuleComplex object.

modifyAttributes

virtual int modifyAttributes(const std::string sAttrName, double dValue);
sAttrName

Name of attribute to change.

dValue

Value to set the attribute to.

The only attribute that can be changed is obviously "WeightedMove_prob".

displayInfo

void displayInfo(const char *pPrefix, float fT, int iCellIndex, int iAgentIndex);
pPrefix

A prefix for the debu message.

fT

Current simulation step.

iCellIndex

Index of current cell.

iAgentIndex

Index of current agent.

This method prints the environment weights for the cell.

isEqual

virtual bool isEqual(Action<T> *pAction, bool bStrict);
pAction

Pointer to an action object to compare with this.

bStrict

Strictness of comparisons (ignored here).

pAction is equal to this, if it is a WeightedMove object whose move probability is the same as the one of this.