TMtxMDScaling Class — Stats Master

class TMtxMDScaling : public TMtxComponent;

Performs multidimensional scaling.

Use TMtxMDScaling component to perform multidimensional scaling on dataset.

How to use TMtxMDScaling component?
1. Drop a TMtxMDScaling component on the form. 2. Set TMtxMDScaling::DataFormat property to define how data will be interpreted. Data can be interpreted as dissimilarities matrix, similarities matrix or raw data matrix. 3. Define TMtxMDScaling::Data, the matrix representing dissimilarities matrix, similarities matrix or raw data.
4. Set TMtxMDScaling::Dimensions to define number of variables in reduced space. 5. Set TMtxMDScaling::DistanceMethod to define how pairwise distance will be calculated. 6. Set TMtxMDScaling::ScalingMethod to define scaling algorithm. Currently only metric (classical) multidimensional scaling algorithm is supported. 7. Call the TMtxMDScaling::Recalc method to trigger calculation.

Results:
1. TMtxMDScaling::Y : Point coordinates in reduced space. 2. TMtxMDScaling::EigenValues : Eigenvalues in reduced space, sorted in descending order. 3. TMtxMDScaling::DHat : Estimated dissimilarities matrix. 4. TMtxMDScaling::Stress : Calculated stress factor.

Examples

cpp

#include "MtxVec.h"
#include "Statistics.h"
#include "StatTools.h"

using namespace Dew;
using namespace Dew::Math;
using namespace Dew::Stats;

void Example()
{
    TMtxMDScaling* mds = new TMtxMDScaling(nullptr);
    // similarities matrix (symmetric with 1.0 on diagonal)
    mds->Data->SetIt(5,5,false, DewArray<double> {
        1.00, 0.3, 0.2, 0.25, 0.33,
        0.30, 1.0, 0.11, 0.21, 0.8,
        0.20, 0.11, 1.0, 0.40, 0.5,
        0.25, 0.21, 0.40, 1.0, 0.05,
        0.33, 0.80, 0.5, 0.05, 1.00});
    mds->DataFormat = TMDDataFormat::mdFormatSimilarities;
    // use "standard" Euclidian metric
    mds->DistanceMethod = TPWDistMethod::pwdistEuclidian;
    // define number of desired dimensions (1)
    mds->Dimensions = 1;
    // Do the math
    mds->Recalc();
    // check Stress, DHat, EigeValues to evaluate GOF if (1) dimension is used
    delete mds;
}

Constructors

Name	Description
TMtxMDScaling (2)

Destructors

Name	Description
~TMtxMDScaling

Properties

Name	Type	Description
AutoUpdate	bool	If true then changing any of the TMtxPCA properties will trigger the TMtxMDScaling::Recalc method.
BlockAssign	bool	Block streaming of specific properties when storing only a "template".
D	TMtx*	Used dissimilarities matrix.
Data	TMtx*	Data to be analyzed by MDS.
DataFormat	TMDDataFormat	Data format.
DHat	TMtx*	Estimated dissimilarities matrix.
Dimensions	int	Reduced dimension size.
Dirty	bool	When any of the TMtxMDScaling properties changes, this property is automatically set to true.
DistanceMethod	TPWDistMethod	Metric for distance calculation.
EditorActive	bool	Returns True, if the component editor is displayed.
EigenValues	TVec*	Reduced space eigenvalues.
Name	DewString
Reference	TReferenceList*	Stores a list of components that have to be notified, when this component is destroyed.
ScalingMethod	TMDScalingMethod	Defines multidimensional scaling algorithm.
Stress	double	Returns multidimensional scaling stress value which is an estimate for GOF.
Y	TMtx*	Reduced space point coordinates.

Methods

Name	Description
AllowStreaming	Returns the negatated value of BlockAssign.
Assign	Assign values of all published properties from Source.
AssignTemplate	Assign values of "template-like" published properties from Source.
EditorClass	To be overriden in descendanr classses.
LoadFromStream	Load the component from Src stream.
LoadTemplateFromFile	Load a template from file.
LoadTemplateFromStream	Load a template from stream.
Recalc	Triggers MDScalling recalculation.
ReferenceRemoved
Reset	Reset is called after loading the data from stream or file.
SaveTemplateToFile	Save template to file.
SaveTemplateToStream	Save template to stream.
SaveToStream	Save the component to Dst stream.

Fields

Name	Type	Description
Tag	intptr_t