annotate chordtools/chord2pitchclasses.m @ 1:8973548174c1 tip

adding tools to repo

%
%CHORD2PITCHCLASSES Convert chord symbol to array of pitch classes
% 
% [pitchclasses, bassclass, success, errormessage] = chord2pitchclasses(chordsymbol, {inversion}, {verbose})
% 
% Converts a chord symbol to an array of integer pitch class values and a
% bass pitch class value. Pitch class values are referenced w.r.t. C = 0.
%
% In the case of the 'no chord' symbol 'N' function returns an empty array
%
% Success = 1 if notes extracted from chordsymbol correctly, 0 otherwise.
% 
% If optional argument 'verbose' is 1, function prints any errormessage to 
% the screen.
% 
% calls:    chord2notes
%           notes2pitchclasses
% 
% returns:  pitchclasses (array of integers)
%           bassclass (integer)           
%           success (boolean)
%           errormessage (string)
%
%
% Author: Christopher Harte,  March 2009
% 
% Copyright: Centre for Digital Music, Queen Mary University of London 2005 
%
% This file is part of the C4DM Chord Toolkit V2.0  
%
% The C4DM Chord Toolkit 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.
%
% The C4DM Chord Toolkit 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 the C4DM Toolkit; if not, write to the Free Software
% Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

%             
function [pitchclasses, bassclass, success, errormessage] = chord2pitchclasses(chordsymbol, inversion, verbose)

% set verbose default to 0
if nargin < 3
    verbose = 0;
end

if nargin < 2
    inversion = 1;
end

errormessage = '';
mainlist = '';
success = 1;
pitchclasses = [];
bassclass = '';
contains = 0;
 
% get constituent notes
[chordnotes, bassnote, success, errormessage] = chord2notes(chordsymbol);

%convert notes and bass to pitch classes
if success && ~isempty(chordnotes)
% find pitchclasses of notes
[pitchclasses, success, errormessage] = notes2pitchclasses(chordnotes);
end

if success && ~isempty(bassnote)
[bassclass, success, errormessage] = note2pitchclass(char(bassnote));

    % check if the bass class is already part of the chord
    if success
        ilength = length(pitchclasses);

        contains = 0;

        for index = 1:ilength
            if bassclass == pitchclasses(index)
                contains = 1;
                if inversion
                    pitchclasses = [pitchclasses(index:end) pitchclasses(1:index-1)];
                end
            end
        end

    end

    %if the note is not already part of the chord then insert it
    if ~contains

        % if inversion=1 then insert at start of pitchclasses
        if inversion
            pitchclasses = [bassclass pitchclasses];
        else
            relpc = mod(pitchclasses-pitchclasses(1),12);
            relbass = mod(bassclass-pitchclasses(1),12);
            
            i=0;
            while(i<ilength)
                if relbass<relpc(i+1)
                    break
                else
                    i=i+1;
                end
            end

            if i==ilength
                pitchclasses = [pitchclasses bassclass];
            else
                pitchclasses = [pitchclasses(1:i) bassclass pitchclasses(i+1:end)];
            end
            
            
            
            
        end
        
    end

end    
    


if success == 0
    errormessage = [errormessage sprintf(['Error in chord2pitchclasses: Couldn''t convert chord "' chordsymbol '"\n'])];   
    if verbose ==1
       fprintf(1,errormessage);
    end
       
       
end