convertMatToAscii.m

%% convertMatToAscii.m  --- Evan Bollig, 2010
% Converts .mat format files to a directory of .mtx files. 
% The .mtx format is plain ascii tuples separated by '\n' with tuple
% elements separated by spaces
% 
% If this routine is run with no arguments a user interface appears for
% the user to select one or more files to convert
%
% Argument matFilename specifies the full/absolute path to a file to
% convert
function [] = convertMatToAscii(matFilename)
    if (nargin < 1)
        % The path is in pth
        [filename,pth] = uigetfile('*.mat', 'Pick one or more MAT-files', 'MultiSelect', 'on');
        if isequal(filename,0) || isequal(pth,0)
            disp('Operation cancelled');
            return
        end
    else
        filename = matFilename;
    end

    % Decompose the file
    if (iscell(filename))
        for i = 1:length(filename)
            decompressFile(filename{i});
        end
    else
        decompressFile(filename);
    end
end


function [] = decompressFile(filename)
[pathstr,file_no_ext,ext,versn] = fileparts(filename);

% Make a directory matching matFilename
mkdir(file_no_ext);

% Foreach variable inside matFilename
data = load(filename)

if (isstruct(data))
    % Write each field to a separate file.
    names = fieldnames(data);
    for i = 1:length(names)
        d = getfield(data, char(names(i)));
        % If data is > 3 dimensions we assume its a full matrix. We write
        % this to matrix market format
        if size(d,2) > 3
            writeToMMFile(d, char(strcat(file_no_ext, '/', names(i), '.mtx')));
        else 
           writeToFile(d, char(strcat(file_no_ext, '/', names(i), '.ascii')));
        end
    end
else
    fprintf('NOT SUPPORTED YET (See Evan Bollig)\n');
end
end

function [] = writeToMMFile(data, filename)
    fprintf('.....Writing ''%s''\n', filename);
    A = sparse(data);
    figure
    spy(A);
    comment = str2mat('Auto-Converted Matrix From convertMatToAscii (Evan Bollig)',[' ',date]);
    mmwrite(filename,A,comment);
end

function [] = writeToFile(data, filename)

fprintf('.....Writing ''%s''\n', filename);

% TODO: write tuple dimensions to the file header, plus number of tuples

fid = fopen(filename,'w+');

[m n] = size(data);

for i = 1:m
    for j = 1:n
        fprintf(fid, '%g ', data(i,j));
    end
    fprintf(fid, '\n');
end

fclose(fid);

end