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InvRapMusic

Namespace: INVLIB  ·  Library: Inverse Library

Python equivalent

mne.beamformer.rap_music in MNE-Python.

#include <inv/inv_rap_music.h>

class INVLIB::InvRapMusic

RAP MUSIC (Recursively Applied and Projected Multiple Signal Classification) source localization algorithm.

Implements the RAP MUSIC scanning algorithm which iteratively identifies correlated source pairs by projecting the signal subspace and re-scanning the lead field. Each iteration finds one dipole (or dipole pair), projects it out of the signal subspace, and repeats until the desired number of sources is found or the residual correlation drops below threshold.

Reference: Mosher & Leahy, IEEE Trans. Signal Process. 47(2), 332-340, 1999.

src/examples/ex_inv_beamformer/main.cpp
// Noise-free data from the two sources with different time courses; RAP-MUSIC scans source pairs.
const int nSamples = 60;
MatrixXd measured(G.rows(), nSamples);
for (int t = 0; t < nSamples; ++t)
    measured.col(t) = g1 * std::sin(0.21 * t) + g2 * std::sin(0.53 * t + 0.4);
QList<InvDipolePair<double>> pairs;
InvRapMusic rap(fwd, false, 1, 0.5); // one correlated pair, subspace correlation >= 0.5
rap.calculateInverse(measured, pairs);
QList<InvDipolePair<double>> powellPairs;
InvPwlRapMusic pwlRap(fwd, false, 1, 0.5); // Powell coordinate search: far fewer pairs, may stop at a local optimum
pwlRap.calculateInverse(measured, powellPairs);

Inheritance​

Public Methods​

InvRapMusic()​

Default constructor creates an empty InvRapMusic algorithm which still needs to be initialized.

InvRapMusic(p_pFwd, p_bSparsed, p_iN, p_dThr)​

Constructor which initializes the InvRapMusic algorithm with the given model.

Parameters:

  • p_pFwd : MNEForwardSolution & The model which contains the gain matrix and its corresponding grid matrix.

  • p_bSparsed : bool True when sparse matrices should be used.

  • p_iN : int The number (default 2) of uncorrelated sources, which should be found. Starting with. the strongest.

  • p_dThr : double The correlation threshold (default 0.5) at which the search for sources stops.

~InvRapMusic()​

init(p_pFwd, p_bSparsed, p_iN, p_dThr)​

Initializes the RAP MUSIC algorithm with the given model.

Parameters:

  • p_pFwd : MNEForwardSolution & The model which contains the gain matrix and its corresponding Grid matrix.

  • p_bSparsed : bool True when sparse matrices should be used.

  • p_iN : int The number (default 2) of uncorrelated sources, which should be found. Starting with. the strongest.

  • p_dThr : double The correlation threshold (default 0.5) at which the search for sources stops.

Returns:

  • bool — true if successful initialized, false otherwise.

calculateInverse(p_fiffEvoked, pick_normal)​

calculateInverse(data, tmin, tstep, pick_normal)​

calculateInverse(p_matMeasurement, p_RapDipoles)​

getName()​

getSourceSpace()​

setStcAttr(p_iSampStcWin, p_fStcOverlap)​

Sets the source estimate attributes.

Parameters:

  • p_iSampStcWin : int Samples per source localization window (default - 1 = not set).

  • p_fStcOverlap : float Percentage of localization window overlap.

Example​

Used in examples​

ex_inv_beamformer​

Inverse library: LCMV and DICS beamformers and the RAP-MUSIC family of dipole scanners.

src/examples/ex_inv_beamformer/main.cpp, line 154
for (int t = 0; t < nSamples; ++t)
    measured.col(t) = g1 * std::sin(0.21 * t) + g2 * std::sin(0.53 * t + 0.4);
QList<InvDipolePair<double>> pairs;
InvRapMusic rap(fwd, false, 1, 0.5); // one correlated pair, subspace correlation >= 0.5
rap.calculateInverse(measured, pairs);
QList<InvDipolePair<double>> powellPairs;
InvPwlRapMusic pwlRap(fwd, false, 1, 0.5); // Powell coordinate search: far fewer pairs, may stop at a local optimum
pwlRap.calculateInverse(measured, powellPairs);
ok &= expect(pairs.size() == 1 && isPair(pairs[0], 10, 50) && pairs[0].m_vCorrelation > 1.0 - 1e-6 && powellPairs.size() == 1 && powellPairs[0].m_vCorrelation > 0.99,
             QString("InvRapMusic/InvPwlRapMusic/InvDipolePair: the exhaustive scan finds sources 10 and 50 (correlation 1), Powell a pair at %1")
                 .arg(powellPairs.isEmpty() ? 0.0 : powellPairs[0].m_vCorrelation, 0, 'f', 4));

ex_inverse_rap_music​

Example of MNEForwardSolution and InvRapMusic application.

src/examples/ex_inverse_rap_music/main.cpp, line 87
QCommandLineOption evokedFileOption("ave", "Path to the evoked/average <file>.", "file", QCoreApplication::applicationDirPath() + "/../resources/data/MNE-sample-data/MEG/sample/sample_audvis-ave.fif");
QCommandLineOption subjectDirectoryOption("subjDir", "Path to subject <directory>.", "directory", QCoreApplication::applicationDirPath() + "/../resources/data/MNE-sample-data/subjects");
QCommandLineOption subjectOption("subj", "Selected <subject>.", "subject", "sample");
QCommandLineOption stcFileOption("stcOut", "Path to stc <file>, which is to be written.", "file", ""); //"InvRapMusic.stc");
QCommandLineOption doMovieOption("doMovie", "Create overlapping movie.", "doMovie", "false");
QCommandLineOption annotOption("annotType", "FsAnnotation type <type>.", "type", "aparc.a2009s");
QCommandLineOption numDipolePairsOption("numDip", "<number> of dipole pairs to localize.", "number", "1");
QCommandLineOption surfOption("surfType", "FsSurface type <type>.", "type", "orig");

ex_clustered_inverse_rap_music_raw​

Example of the computation of a raw clustered inverse rap music.

src/examples/ex_clustered_inverse_rap_music_raw/main.cpp, line 428
//
// Compute inverse solution
//
InvRapMusic t_rapMusic(t_clusteredFwd, false, numDipolePairs);

Also used in ex_inverse_pwl_rap_music.

Authors of this file​