EMG_feat_extr.m

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%This file is part of TEAP.
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%> @file EMG_feat_extr.m
%> @brief Computes Skin EMG featuEMG
%> @param  EMGsignal: the EMG  signal.
%> @param  varargin: you can choose which features to extract (see featureSelector)
%>          the list of available features is:
%>             - mean_: average temprature
%>             - std_: standard deviation of the EMG
%>             - kurtosis_: Kurtosis of the EMG
%>             - skewness_: skewness of the EMG
%>             - EMG_power: power spectral power above 20Hz
 
%> @retval  EMG_feats: list of featuEMG values
%> @retval EMG_feats_names: names of the computed features (it is good pratice to
%>                        check this vector since the order of requested features
%>                        can be different than the requested one)
%> @author Copyright Frank Villaro-Dixon, 2015
 
%
%> @b WARNING: this function will give 'strange' results when applied on a relative
%>        signal
%
function [EMG_feats, EMG_feats_names] = EMG_feat_extr(EMGsignal, varargin)
 
% Check inputs and define unknown values
narginchk(1, Inf);
 
%Make sure we have a EMG signal
EMGsignal = EMG__assert_type(EMGsignal);
 
 
% Define full feature list and get featuEMG selected by user
featuEMGNames = {'mean_', 'std_', 'kurtosis_','skewness_','EMG_power'};
EMG_feats_names = featuresSelector(featuEMGNames,varargin{:});
 
%If some featuEMG are selected
if(~isempty(EMG_feats_names))
    samprate = Signal__get_samprate(EMGsignal);
    %statistical moments
    if any(strcmp('mean_',EMG_feats_names)) || any(strcmp('std_',EMG_feats_names)) || any(strcmp('kurtosis_',EMG_feats_names)) || any(strcmp('skewness_',EMG_feats_names))
        [mean_,std_, kurtosis_, skewness_] = Signal_feat_stat_moments(EMGsignal);
    end
    %EMG power above 20Hz; this is associated with muscule contractions
    if any(strcmp('EMG_power',EMG_feats_names))
        bands = [20,samprate/2];
        EMG_power = Signal_feat_bandEnergy(EMGsignal, bands)';
    end
 
    %Write the values to the final vector output
    for (i = 1:length(EMG_feats_names))
        eval(['EMG_feats(i,:) = ' EMG_feats_names{i} ';']);
    end
 
else %no featuEMG selected
    EMG_feats = [];
end