SimpleWeightTuner Class Reference

Class SimpleWeightTuner. More...

#include <simple_weight_tuner.h>

Classes
class	Impl
	Private implementation of the Stopwatch Utility. More...

Public Member Functions
	SimpleWeightTuner (CARLsim *sim, double errorMargin=1e-3, int maxIter=100, double stepSizeFraction=0.5)
	Creates a new instance of class SimpleWeightTuner. More...
	~SimpleWeightTuner ()
	Destructor. More...
bool	done (bool printMessage=false)
	Determines whether a termination criterion has been met. More...
void	iterate (int runDurationMs=1000, bool printStatus=true)
	Performs an iteration step of the tuning algorithm. More...
void	reset ()
	Resets the algorithm to initial conditions. More...
void	setConnectionToTune (short int connId, double initWt=-1.0, bool adjustRange=true)
	Sets up the connection to tune. More...
void	setTargetFiringRate (int grpId, double targetRate)
	Sets up the target firing rate of a specific group. More...

Detailed Description

The SimpleWeightTuner utility is a class that implements a simple search algorithm inspired by the bisection method.

The usage scenario is to tune the weights of a specific connection (collection of synapses) so that a specific neuron group fires at a predefined target firing rate—without having to recompile the network. A complete code example can be found in the Tutorial subfolder 12_advanced_topics/simple_weight_tuner.

Example usage:

// assume CARLsim object exists with the following components:
int gOut=sim->createGroup("out", nNeur, EXCITATORY_NEURON);
sim->setNeuronParameters(gOut, 0.02f, 0.2f, -65.0f, 8.0f);
int gIn=sim->createSpikeGeneratorGroup("in", nNeur, EXCITATORY_NEURON);
int c0=sim->connect(gIn, gOut, "random", RangeWeight(initWt), 0.1f, RangeDelay(1,10));
// etc.
sim->setupNetwork();

   // use weight tuner to find the weights that give 27.4 Hz spiking in gOut
SimpleWeightTuner SWT(sim, 0.01, 100);
SWT.setConnectionToTune(c0, 0.0);
SWT.setTargetFiringRate(gOut, 27.4);

while (!SWT.done()) {
   SWT.iterate();
}

See also

Tutorial: 12.4.1 Simple Weight Tuner

Code example: tutorial/12_advanced_topics/simple_weight_tuner/main_simple_weight_tuner.cpp

Since

v3.0

Definition at line 92 of file simple_weight_tuner.h.

Constructor & Destructor Documentation

SimpleWeightTuner()

SimpleWeightTuner	(	CARLsim *	sim,
		double	errorMargin = 1e-3,
		int	maxIter = 100,
		double	stepSizeFraction = 0.5
	)

This method creates a new instance of class SimpleWeightTuner. A SimpleWeightTuner can be used to tune weights on the fly; that is, without having to recompile and build a network. This is useful especially for tuning feedforward weights in large-scale networks that would otherwise take a long time to repeatedly build. For tuning in more complex situations please refer to ECJ (Parameter Tuning Interface).

Parameters

[in]	sim	pointer to CARLsim object
[in]	errorMargin	termination condition for error margin on target firing rate
[in]	maxIter	termination condition for max number of iterations
[in]	stepSizeFraction	step size for increasing/decreasing weights per iteration

Since

v3.0

See also

ch10_ecj

Definition at line 302 of file simple_weight_tuner.cpp.

~SimpleWeightTuner()

~SimpleWeightTuner

(

)

Cleans up all objects related to SimpleWeightTuner.

Since

v3.0

Definition at line 304 of file simple_weight_tuner.cpp.

Member Function Documentation

done()

bool done

(

bool

printMessage = false

)

This method checks whether a termination criterion has been met, in which case true is returned.

The algorithm will terminate if any of the following criteria have been met:

• The firing rate is close enough to the target: `currentFiring - targetFiring < errorMargin'
• The maximum number of iteration step has been reached: numberOfIter > maxIter

Parameters

[in]

printMessage

flag whether to print message upon termination

Since

v3.0

Definition at line 313 of file simple_weight_tuner.cpp.

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iterate()

void iterate	(	int	runDurationMs = 1000,
		bool	printStatus = true
	)

This method runs the CARLsim network for a time period of runDurationMs milliseconds, throughout which a SpikeMonitor is recording the firing rate of the group ID specified in setTargetFiringRate.

At the end of the iteration step the recorded firing rate is compared to the target firing rate, and the relative error is computed. If the error is smaller than the specified error margin, the algorithm terminates. If the maximum number of iteration steps is reached, the algorithm terminates. Otherwise the weights of the connection ID specified in setConnectionToTune() are updated, and the next iteration step is ready to be performed.

Parameters

[in]	runDurationMs	time to run the CARLsim network (ms)
[in]	printStatus	whether to print stats at the end of the iteration

Since

v3.0

See also

CARLsim::runNetwork

Definition at line 312 of file simple_weight_tuner.cpp.

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reset()

void reset

(

)

This method resets the algorithm to the initial conditions. It is implicitly called at the beginning and whenever setTargetFiringRate or setConnectionToTune has been called.

Since

v3.0

Definition at line 314 of file simple_weight_tuner.cpp.

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setConnectionToTune()

void setConnectionToTune	(	short int	connId,
		double	initWt = -1.0,
		bool	adjustRange = true
	)

This method sets up the connection ID to tune. The algorithm will repeatedely change the synaptic weights of this connection until the firing rate of a group (speficied via setTargetFiringRate) matches a certain target firing rate (specified in SimpleWeightTuner).

If the initial weight is set to a negative value, the algorithm will start with whatever weights have been specified when setting up the connection in CARLsim::connect. Otherwise a bias will be applied to all weights such that initWt matches the field initWt of the connection's RangeWeight struct.

If adjustRange is set to true, the [minWt,maxWt] ranges will be adjusted automatically should the weight go out of bounds.

See also

CARLsim::connect

RangeWeight

CARLsim::biasWeights

Since

v3.0

Definition at line 306 of file simple_weight_tuner.cpp.

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setTargetFiringRate()

void setTargetFiringRate	(	int	grpId,
		double	targetRate
	)

This method sets up the target firing rate (Hz) of a specific group to achieve via changing the weights of the connection specified in setConnectionToTune.

A SpikeMonitor will be set up for the group if it does not already exist. SpikeMonitor::getPopMeanFiringRate will be used to determine the group's firing activity, and compare it to targetRate in order to compute the error margin.

Parameters

[in]	grpId	the group ID
[in]	targetRate	target firing rate (Hz) of the group

Attention

If a SpikeMonitor already exists for this group, SimpleWeightTuner will use the same one and turn PersistentMode off.

Since

v3.0

See also

SpikeMonitor

Definition at line 309 of file simple_weight_tuner.cpp.

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

• simple_weight_tuner.h
• simple_weight_tuner.cpp