function [scoreMatrix,parameter] = threshSM(SM,parameter)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Name: threshSM.m
% Date of Revision: 2013-06
% Programmer: Nanzhu Jiang, Peter Grosche, Meinard Müller
% http://www.audiolabs-erlangen.de/resources/MIR/SMtoolbox/
%
%
% Description:
% This function implements four different thresholding techniques to a
% similarity matrix.
% 1 - absolute (value)
% 2 - relative (number of cells)
% 3 - relative (amount of total value)
% 4 - relative (number of cells in each row/column)
%
%
% Input:
% SM : a similarity matrix
% parameter (optional): parameter struct with fields
% .threshTechnique : which techqnique to use
% .threshValue : threshold value, note that depends on
% threshTechnique, this value could be either
% relative threshold or absolute threshold.
% .applyScale : whether to apply scaling or not
% .penalty : give very small value an extra penalty
% .applyBinarize: whether to apply binarization or not
%
% Output:
% scoreMatrix : the thresholded SM.
% parameter (optional) : if any field in the inpur parameter is not
% setted, this output parameter allows users
% to see which settings are used.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% Reference:
% If you use the 'SM toobox' please refer to:
% [MJG13] Meinard Müller, Nanzhu Jiang, Harald Grohganz
% SM Toolbox: MATLAB Implementations for Computing and Enhancing Similarity Matrices
% Proceedings of the 53rd Audio Engineering Society Conference on Semantic Audio, London, 2014.
%
% License:
% This file is part of 'SM Toolbox'.
%
% 'SM Toolbox' is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 2 of the License, or
% (at your option) any later version.
%
% 'SM Toolbox' is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with 'SM Toolbox'. If not, see
% .
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Check parameters
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
if nargin<2
parameter = [];
end
if ~isfield(parameter,'threshTechnique')
parameter.threshTechnique = 2;
end
if ~isfield(parameter,'threshValue')
parameter.threshValue = 0.2;
end
if ~isfield(parameter,'applyScale')
parameter.applyScale = 0;
end
if ~isfield(parameter,'penalty')
parameter.penalty = 0;
end
if ~isfield(parameter,'applyBinarize')
parameter.applyBinarize = 0;
end
%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Thresholding
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
scoreMatrix = SM;
clear threshAbs;
switch parameter.threshTechnique
case 1 % absolute
threshAbs = parameter.threshValue;
scoreMatrix(scoreMatrix < threshAbs) = 0;
case 2 % fixed number of cells
numCutCell = numel(SM)*(1-parameter.threshValue);
valuesSort = sort(scoreMatrix(:));
threshAbs = valuesSort(round(numCutCell));
scoreMatrix(scoreMatrixthreshAbs,1,'first');
scoreMatrix(scoreMatrix~~ 0,1,'first');
minValue = values(pos);
maxValue = max(max(scoreMatrix));
if(isequal(maxValue,Inf))
warning('matrix contains Infinity values, scaling result might not be reliable');
end
scoreMatrix = (scoreMatrix - minValue) /(maxValue - minValue);
end
%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Penalty/Binariziation
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
scoreMatrix(scoreMatrixeps) = 1;
scoreMatrix(scoreMatrix<=eps) = 0;
end
end
~~