Merging Meryem Yucel's new user function: Performs a linear fit and removes it...

% SYNTAX:

% data2 = hmrR_PreprocessOD_LinearFit(data, turnon)

%

% UI NAME:

% LinearFit

%

% DESCRIPTION:

% Perform a linear fit and removes it from the time course data.

%

% INPUT:

% data - SNIRF data type containing data time course to filter, time vector, and channels.

% turnon - 1 turns the function on

%

% OUTPUT:

% data2 - SNIRF data type containing the filtered data time course data

%

% USAGE OPTIONS:

% Linear_Fit_OpticalDensity: dod = hmrR_PreprocessOD_LinearFit(dod, turnon)

%

% PARAMETERS:

% turnon: [1]

function [data2] = hmrR_PreprocessOD_LinearFit( data, turnon )

if turnon == 1

    if isa(data, 'DataClass')

        data2 = DataClass().empty();

    end

    for ii=1:length(data)

        if isa(data, 'DataClass')

            data2(ii) = DataClass(data(ii));

        end

        X = data2(ii).GetDataTimeSeries();

        t = data2(ii).GetTime();

        for j = 1:size(X,2) % channel

            p = polyfit(t,X(:,j),1);

            yfit = polyval(p,t);

            X_yfit(:,j) = X(:,j)-yfit;

        end

    end

    data2(ii).SetDataTimeSeries(X_yfit);

else

    data2 = data;

end