readMM_2D(file,nrows,flagstr)

function data = readMM_2D(file,nrows,flagstr)
%Read 2-D matrix saved with Mathematica 'Put' command.
%READMM_2D(file,nrows) reads data from the full path+filename specified by
%'file' and parses the data into the number of rows specified by 'nrows'.
%
% If the number of rows is specified the function uses TXT2MAT to read a
% Mathematica formatted 2D data array. If number of rows is not specified,
% or if TXT2MAT is not available, the function reads the file with TEXTREAD
% and automatically determines the number of rows and columns for the input
% data.
%
% Inputs:
%         file    -- string variable; fully specified filename
%         nrows   -- numeric scalar; number of rows in data file
%         flagstr -- 'fast' specifies TXT2MAT algorithm (default)
%                    'slow' specifies TEXTREAD algorithm
%
%  Example:
%           numrows = 1248;
%           myfile = 'C:\somefile.txt';
%           A = readMM_2D(myfile,numrows);
%
%             ans = <1248x1248 double>
%

% David Sedarsky
% November, 2008


if nargin == 0,
    [FileName,PathName] = uigetfile('*.*','Select data file');
    % If "Cancel" is selected then return
    if isequal([FileName,PathName],[0,0])
        return
    else
        file = fullfile(PathName,FileName);
    end
    nrows = 0;
    flagstr = 'slow';
end
if nargin == 1,
    nrows = 0;
    flagstr = 'slow';
end
if nargin == 2,
    flagstr = 'fast';
end

if ~isnumeric(nrows)
    flagstr = 'slow';
end

%fast read process based on TXT2MAT
if strcmpi(flagstr,'fast'),
%     disp('running fast routine');
    if exist('txt2mat')==2,
        a = txt2mat(file,...
        'ReadMode','block',...
        'NumColumns',nrows,...
        'ReplaceChar',{'{}, '});
    else
        warning('TXT2MAT not found, using slower TEXTREAD process.');
        flagstr = 'slow';
    end
end
if strcmpi(flagstr,'fast'),
        %reshape matrix
        data = reshape(a,nrows,nrows).';
end

%slow read process based on TEXTREAD
if ~strcmpi(flagstr,'fast'),
%     disp('running slow routine');
    %read entire file as cell string
    a = textread(file,'%s','delimiter',',');

    %search for first '}' character (indicates the end of a column)
    for count=1:length(a)
        if ~isempty(strfind(cell2mat(a(count)),'}'))
            break
        end
    end
    ncols = count;
    nrows = length(a)/ncols;

    %clean braces '{' and '}' from data
    a = strrep(a,'{','');
    a = strrep(a,'}','');
    %convert cell array to char
    a = char(a);
    %convert string array to numeric
    a = str2num(a);
    %reshape matrix
    data = reshape(a,ncols,nrows);
end