function logData(datafile, trial, varargin)
%--------------------------------------------------------------------------
% USAGE: logData(datafile, trial, [recordedVariables],...)
%
% Creates a Data struct with each field representing a variable that has
% been specified to be saved.
%
% datafile: Path and name of subject's datafile. Should be a .mat file,
% containing a Data structure for that subject.
%
% trial: Trial number for recording. If variable is a single instance (e.g.
% group membership, date run, etc., trial = 1
%
% recordedVariables:
%
% USAGE 1: logData(datafile, [trial], var1, var2, var3)
%
% This usage will write the variables var1 etc. into the Data structure,
% using the names 'var1', etc.
%
% USAGE 2: logData(datafile, [trial], Struct)
%
% This usage is a more compact way of logging the data. Struct contains all
% the variables for that trial, each with its own field (e.g. Struct.var1,
% Struct.var2 etc.). Each field in Struct will be appended to the Data
% struct.
%--------------------------------------------------------------------------


% Load the datafile where the information is to be saved. If the requested
% datafile doesn't exist, create it, but give a warning that one is doing so.
if exist(datafile,'file')

    load(datafile); % loads the Data structure into memory for appending

else

    warning(['Requested datafile (', datafile, ') does not exist!', ...
             'The file will be created in the current directory.']);

end

% Loop over the number of inputs (minus the datafilename and the trial
% number), and for each input, determine whether it is a single value (in
% which case revert to usage #1) or a structure (in which case revert to
% usage #2).
for var = 1:nargin - 2

    if ~isstruct(varargin{var})
        % USAGE 1: use the inputname function to retrieve the name value of
        % each variable submitted to the function, then store this variable
        % in the corresponding field of the Data structure.
        Data.(inputname(var + 2)){trial} = varargin{var};
    else

        % USAGE 2: given a structure with field names var1, var2, etc.,
        % save the data in each field to the appropriate location in the
        % corresponding field of the Data structure.
        TempStruct = varargin{var};
        varnames = fieldnames(TempStruct);

        for field = 1:length(varnames)
            Data.(varnames{field}){trial} = TempStruct.(varnames{field});
        end

    end

end

% Having finished appending the data into the Data structure, save it
save(datafile,'Data');

Published with MATLAB® R2015b