import PerimeterConstraint from 'Artistoo/src/hamiltonian/PerimeterConstraint.js'

public class | source

PerimeterConstraint

Extends:

Constraint → SoftConstraint → PerimeterConstraint

Implements the perimeter constraint of Potts models. A cell's "perimeter" is the number over all its borderpixels of the number of neighbors that do not belong to the cell itself.

This constraint is typically used together with Adhesion and {@VolumeConstraint}.

See PerimeterConstraint#constructor for the required parameters.

Example:

// Build a CPM and add the constraint
let CPM = require( "path/to/build" )
let C = new CPM.CPM( [200,200], {
	T : 20,
	J : [[0,20],[20,10]],
	V : [0,500],
	LAMBDA_V : [0,5]
})
C.add( new CPM.PerimeterConstraint( {
	P : [0,260],
	LAMBDA_P : [0,2] 	
} ) )

// Or add automatically by entering the parameters in the CPM
let C2 = new CPM.CPM( [200,200], {
	T : 20,
	J : [[0,20],[20,10]],
	V : [0,500],
	LAMBDA_V : [0,5],
	P : [0,260],
	LAMBDA_P : [0,2]
})

Test:

Constructor Summary

Public Constructor
public	constructor(conf: object) The constructor of the PerimeterConstraint requires a conf object with parameters.

Member Summary

Public Members
public set	CPM(C: CPM) Set the CPM attached to this constraint.
public	cellperimeters: CellObject The perimeter size of each pixel is tracked.

Method Summary

Public Methods
public	confChecker() This method checks that all required parameters are present in the object supplied to the constructor, and that they are of the right format.
public	deltaH(sourcei: IndexCoordinate, targeti: IndexCoordinate, src_type: CellId, tgt_type: CellId): number Method to compute the Hamiltonian for this constraint.
public	initializePerimeters() This method initializes the this.cellperimeters object when the constraint is added to a non-empty CPM.
public	postSetpixListener(i: IndexCoordinate, t_old: CellId, t_new: CellId) The postSetpixListener of the PerimeterConstraint ensures that cell perimeters are updated after each copy in the CPM.

Inherited Summary

From class Constraint
public get abstract	CONSTRAINT_TYPE This method is actually implemented in the subclass.
public set	CPM(C: CPM) This function attaches the relevant CPM to this constraint, so that information about this cpm can be requested from the constraint.
public get	parameters: object: * Get the parameters of this constraint from the conf object.
public	C: CPM CPM on which this constraint acts.
public	conf: object Configuration object for this constraint.
public abstract	cellParameter(param: string, cid: CellId): any Get a cellid or cellkind-specific parameter for a constraint.
public abstract	confChecker() The optional confChecker method should verify that all the required conf parameters are actually present in the conf object and have the right format.
public	paramOfCell(param: string, cid: CellId): any Get a cellId specific parameter, only used if CPMEvol is used: looks whether the requested parameter is overwritten in an @object Cell and otherwise returns @function paramOfKind
public	paramOfKind(param: string, cid: CellId): any Returns a cellKind specfic variable: Assumes that the parameter is indexable by cellkind.

From class SoftConstraint
public get	CONSTRAINT_TYPE: string: string Let the CPM know that this is a soft constraint, so return 'soft'.
public abstract	deltaH(src_i: IndexCoordinate, tgt_i: IndexCoordinate, src_type: CellId, tgt_type: CellId): number Soft constraints must have a deltaH method to compute the Hamiltonian.

Public Constructors

public constructor(conf: object) source

The constructor of the PerimeterConstraint requires a conf object with parameters.

Override:

Constraint#constructor

Params:

Name	Type	Attribute	Description
conf	object		parameter object for this constraint
conf.LAMBDA_P	PerKindNonNegative		strength of the perimeter constraint per cellkind.
conf.P	PerKindNonNegative		Target perimeter per cellkind.

Public Members

public set CPM(C: CPM) source

Set the CPM attached to this constraint.

Override:

Constraint#CPM

public cellperimeters: CellObject source

The perimeter size of each pixel is tracked.

Public Methods

public confChecker() source

This method checks that all required parameters are present in the object supplied to the constructor, and that they are of the right format. It throws an error when this is not the case.

Override:

Constraint#confChecker

public deltaH(sourcei: IndexCoordinate, targeti: IndexCoordinate, src_type: CellId, tgt_type: CellId): number source

Method to compute the Hamiltonian for this constraint.

Override:

SoftConstraint#deltaH

Params:

Name	Type	Attribute	Description
sourcei	IndexCoordinate		coordinate of the source pixel that tries to copy.
targeti	IndexCoordinate		coordinate of the target pixel the source is trying to copy into.
src_type	CellId		cellid of the source pixel.
tgt_type	CellId		cellid of the target pixel.

Return:

number

the change in Hamiltonian for this copy attempt and this constraint.

public initializePerimeters() source

This method initializes the this.cellperimeters object when the constraint is added to a non-empty CPM.

public postSetpixListener(i: IndexCoordinate, t_old: CellId, t_new: CellId) source

The postSetpixListener of the PerimeterConstraint ensures that cell perimeters are updated after each copy in the CPM.

Params:

Name	Type	Attribute	Description
i	IndexCoordinate		the coordinate of the pixel that is changed.
t_old	CellId		the cellid of this pixel before the copy
t_new	CellId		the cellid of this pixel after the copy.

Listen:

setpixi

because when a new pixel is set (which is determined in the CPM), some of the cell perimeters will change.