increasing precison of num2str for dlmcell function.

function dlmcell(file,cell_array,varargin)
%%<><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> %%
% <><><><><>     dlmcell - Write Cell Array to Text File      <><><><><> %
% <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> %
%                                                 Version:    01.06.2010 %
%                                                     (c) Roland Pfister %
%                                             [e-mail] %
%                        ...with many thanks to George Papazafeiropoulos %
%                        for his corrections and improvements.           %
% 1. Synopsis                                                            %
%                                                                        %
% A single cell array is written to an output file. Cells may consist of %
% any combination of (a) numbers, (b) letters, or (c) words. The inputs  %
% are as follows:                                                        %
%                                                                        %
%       - file       The output filename (string).                       %
%       - cell_array The cell array to be written.                       %
%       - delimiter  Delimiter symbol, e.g. ',' (optional;               %
%                    default: tab ('\t'}).                               %
%       - append     '-a' for appending the content to the               %
%                    output file (optional).                             %
%                                                                        %
% 2. Example                                                             %
%                                                                        %
%         mycell = {'Numbers', 'Letters', 'Words','More Words'; ...      %
%                    1, 'A', 'Apple', {'Apricot'}; ...                   %
%                    2, 'B', 'Banana', {'Blueberry'}; ...                %
%                    3, 'C', 'Cherry', {'Cranberry'}; };                 %
%         dlmcell('mytext.txt',mycell);                                  %
%                                                                        %
% <><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><><> %

%%Check input arguments
if nargin < 2
    disp('Error - Give at least two input arguments!');
    return;
elseif nargin > 4
    disp('Error - Do not give more than 4 input arguments!');
    return;
end
if ~ischar(file)
    disp(['Error - File input has to be a string (e.g. ' ...
        char(39) 'output.txt' char(39) '!']);
    return;
end;
if ~iscell(cell_array)
    disp('Error - Input cell_array not of the type "cell"!');
    return;
end;
delimiter = '\t';
append = 'w';
if nargin > 2
    for i = 1:size(varargin,2)
        if strcmp('-a',varargin{1,i}) == 1
            append = 'a';
        else
            delimiter = varargin{1,i};
        end;
    end;
end

%%Open output file and prepare output array.
output_file = fopen(file,append);
output = cell(size(cell_array,1),size(cell_array,2));

%%Evaluate and write input array.
for i = 1:size(cell_array,1)
    for j = 1:size(cell_array,2)
        if numel(cell_array{i,j}) == 0
            output{i,j} = '';
            % Check whether the content of cell i,j is
            % numeric and convert numbers to strings.
        elseif isnumeric(cell_array{i,j}) || islogical(cell_array{i,j})
            output{i,j} = num2str(cell_array{i,j}(1,1));

              % Check whether the content of cell i,j is another cell (e.g. a
              % string of length > 1 that was stored as cell. If cell sizes
              % equal [1,1], convert numbers and char-cells to strings.
              %
              % Note that any other cells-within-the-cell will produce errors
              % or wrong results.
          elseif iscell(cell_array{i,j})
              if size(cell_array{i,j},1) == 1 && size(cell_array{i,j},1) == 1
                  if isnumeric(cell_array{i,j}{1,1})
                      output{i,j} = num2str(cell_array{i,j}{1,1}(1,1));
                  elseif ischar(cell_array{i,j}{1,1})
                      output{i,j} = cell_array{i,j}{1,1};
                  end;
              end;

              % If the cell already contains a string, nothing has to be done.
          elseif ischar(cell_array{i,j})
              output{i,j} = cell_array{i,j};
          end;

          % Cell i,j is written to the output file. A delimiter is appended for
          % all but the last element of each row. At the end of a row, a newline
          % is written to the output file.
          if j < size(cell_array,2)
              fprintf(output_file,['%s',delimiter],output{i,j});
          else
              fprintf(output_file,'%s\r\n',output{i,j});
          end
      end;
  end;

%%Close output file.
fclose(output_file);

end

%when applying num2str function only 4 numbers after the point (floating point) extracting. Is there a way to increase the precision for doubles?

Answer 1

[Robert Cumming]

edit

So its not a display format issue, looking at the help for str2num you can see that it indicates that you can specify the precision, i.e.

change your line to:

num2str(cell_array{i,j}(1,1),10)

to make the number have extra decimal places in the string conversion

---------------------------------------------------------------------

Are you sure this isn't a display format issue:

str = '1.23456789'
>> str2num ( str )
ans =
  1.2346
>> format long
>> str2num ( str )
ans =
 1.234567890000000

[sermet]

no it isn't related format issue, you can try to run this function with format long then look the result.

[sermet]

I tried that but it did not work

[Robert Cumming]

it works for me - on R2014a.

Another (better) solution is to write the number to file directly that way you don't need to do the conversion to a str, e.g:

fprintf ( output_file, '%8.6f%s', number, delimiter )