%% (Internal) Find modulus maxima in a signal
%
% Function which returns the indexes of vector x in which there are
% local modulus maxima or minima whose modulus is greater than
% threshold.
% if signo is 0, it doesn't matter, if signo is +1 or -1, it only searchs
% for modulus maxima positive or negative
% t_restriction: time restriction. Doesnt allow modmax's closer than
% n_greater. In order to restrict the amount of detections, just keep the
% n_greater max_mod found. If more than one modmax, the bigger wins.
% pb a progress bar object to track evolution of the algorithm in big
% signals
%
% [indexes max_mod] = modmax(x, first_samp, threshold, signo, t_restriction, n_greater)
%
% Arguments:
%
% + x: the signal
%
% + first_samp: analyze signal from first_samp sample
%
% + threshold: an amplitude threshold to consider maxima
%
% + signo: sign of the maxima
%
% + t_restriction: time restriction between adjacent maximums
%
% + n_greater: return only the n_greater maxima
%
% Output:
%
% + indexes : the indexes of the modulus maxima
%
% + max_mod: the values of the modulus maxima
%
% Example:
%
% Author: Juan Pablo MartÃnez, Rute Almeida
% adapted by Mariano Llamedo Soria llamedom@electron.frba.utn.edu.ar
% Version: 0.1 beta
% Last update: 14/5/2014
% Birthdate : 21/4/2015
% Copyright 2008-2015
%
function [indexes max_mod] = modmax(x, first_samp, threshold, signo, t_restriction, n_greater)
lx = size(x,1);
indexes = [];
max_mod = [];
if( nargin < 2 || isempty(first_samp) )
first_samp = [2 lx];
else
if( length(first_samp) < 2 )
first_samp = [max(2,first_samp) lx];
else
first_samp(1) = max(2,first_samp(1));
first_samp(2) = min(lx,first_samp(2));
end
end
if( nargin < 3 || isempty(threshold) )
threshold = 0;
end
if( nargin < 4 || isempty(signo) )
signo = 0;
end
bWithPB = false;
if( lx > 10e5 )
bWithPB = true;
pb = progress_bar('Modmax function');
end
if( lx > first_samp(1) )
s = sign(x);
x = abs(x);
sample_curr_idx = first_samp(1):first_samp(2)-1;
sample_prev_idx = (first_samp(1)-1):first_samp(2)-2;
sample_next_idx = (first_samp(1)+1):first_samp(2);
localmax = ( x(sample_curr_idx,:) >= x(sample_prev_idx,:) ) ...
& ( x(sample_curr_idx,:) > x(sample_next_idx,:) ...
& x( sample_curr_idx,:) >= threshold) ...
& ( s(sample_curr_idx,:)*signo >=0 ); % if 0,it doesnt matter
iAux = false(size(x));
iAux(sample_curr_idx,:) = localmax;
indexes = find(iAux);
max_mod = x(indexes) .* s(indexes);
end
if( nargin < 5 || isempty(t_restriction) )
t_restriction = 0;
end
if( t_restriction > 0 )
aux_idx = [];
ii = 1;
bRefine = false;
if( bWithPB )
pb.reset();
end
lindexes = length(indexes);
if( bWithPB )
pb.Loops2Do = lindexes;
end
[~, aux_sorted_mod_idx] = sort(x(indexes), 'descend');
while( ii < lindexes )
if( bWithPB )
pb.start_loop();
end
if( ~isnan(indexes(aux_sorted_mod_idx(ii))) )
indexes_inside_idx = find( indexes >= (indexes(aux_sorted_mod_idx(ii)) - t_restriction) & indexes <= (indexes(aux_sorted_mod_idx(ii))+t_restriction) );
indexes_inside_idx(indexes_inside_idx == aux_sorted_mod_idx(ii)) = [];
if( ~isempty(indexes_inside_idx) )
indexes(indexes_inside_idx) = nan;
end
end
ii = ii+1;
if( bWithPB )
pb.LoopsDone = ii;
pb.checkpoint('');
pb.end_loop();
end
end
indexes(isnan(indexes)) = [];
max_mod = x(indexes) .* s(indexes);
end
if( bWithPB )
clear pb
end
if( nargin < 6 || isempty(n_greater) )
n_greater = realmax;
end
lindexes = length(indexes);
if( n_greater < lindexes )
[~, aux_idx] = sort(abs(max_mod), 'descend');
indexes = indexes(aux_idx(1:n_greater));
max_mod = max_mod(aux_idx(1:n_greater));
[indexes, aux_idx] = sort(indexes);
max_mod = max_mod(aux_idx);
end