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lib/AI/ParticleSwarmOptimization.pm  view on Meta::CPAN

In addition to any user provided parameters the list of values representing the
current particle position in the hyperspace is passed in. There is one value per
hyperspace dimension.

=item I<-inertia>: positive or zero number, optional

Determines what proportion of the previous velocity is carried forward to the
next iteration. Defaults to 0.9

See also I<-meWeight> and I<-themWeight>.

=item I<-iterations>: number, optional

Number of optimization iterations to perform. Defaults to 1000.

=item I<-meWeight>: number, optional

Coefficient determining the influence of the current local best position on the
next iterations velocity. Defaults to 0.5.

See also I<-inertia> and I<-themWeight>.

=item I<-numNeighbors>: positive number, optional

Number of local particles considered to be part of the neighbourhood of the
current particle. Defaults to the square root of the total number of particles.

=item I<-numParticles>: positive number, optional

Number of particles in the swarm. Defaults to 10 times the number of dimensions.

=item I<-posMax>: number, optional

Maximum coordinate value for any dimension in the hyper space. Defaults to 100.

=item I<-posMin>: number, optional

Minimum coordinate value for any dimension in the hyper space. Defaults to
-I<-posMax> (if I<-posMax> is negative I<-posMin> should be set more negative).

=item I<-randSeed>: number, optional

Seed for the random number generator. Useful if you want to rerun an
optimization, perhaps for benchmarking or test purposes.

=item I<-randStartVelocity>: boolean, optional

Set true to initialize particles with a random velocity. Otherwise particle
velocity is set to 0 on initalization.

A range based on 1/100th of -I<-posMax> - I<-posMin> is used for the initial
speed in each dimension of the velocity vector if a random start velocity is
used.

=item I<-stallSpeed>: positive number, optional

Speed below which a particle is considered to be stalled and is repositioned to
a new random location with a new initial speed.

By default I<-stallSpeed> is undefined but particles with a speed of 0 will be
repositioned.

=item I<-themWeight>: number, optional

Coefficient determining the influence of the neighbourhod best position on the
next iterations velocity. Defaults to 0.5.

See also I<-inertia> and I<-meWeight>.

=item I<-exitPlateau>: boolean, optional

Set true to have the optimization check for plateaus (regions where the fit
hasn't improved much for a while) during the search. The optimization ends when
a suitable plateau is detected following the burn in period.

Defaults to undefined (option disabled).

=item I<-exitPlateauDP>: number, optional

Specify the number of decimal places to compare between the current fitness
function value and the mean of the previous I<-exitPlateauWindow> values.

Defaults to 10.

=item I<-exitPlateauWindow>: number, optional

Specify the size of the window used to calculate the mean for comparison to
the current output of the fitness function.  Correlates to the minimum size of a
plateau needed to end the optimization.

Defaults to 10% of the number of iterations (I<-iterations>).

=item I<-exitPlateauBurnin>: number, optional

Determines how many iterations to run before checking for plateaus.

Defaults to 50% of the number of iterations (I<-iterations>).

=item I<-verbose>: flags, optional

If set to a non-zero value I<-verbose> determines the level of diagnostic print
reporting that is generated during optimization.

The following constants may be bitwise ored together to set logging options:

=over 4

=item * kLogBetter

prints particle details when its fit becomes bebtter than its previous best.

=item * kLogStall

prints particle details when its velocity reaches 0 or falls below the stall
threshold.

=item * kLogIter

Shows the current iteration number.