MATLAB: Dlmwrite help – including column and row numbers in output

column numbersdlmwriteMATLABrow numbers

Greetings,

I am using dlmwrite along with 'delimiter','\r' to export matrix data to individual lines in a txt. Is it possible to also include both the data's original matrix column number and row number on the same line as the data? Essentially producing 3 columns per line in the output txt file. The location in the original matrix is very important, and I would like to report this somehow in an easily readable format.

Thank you.

Best Answer

One way....

[i,j]=ind2sub(size(A),1:numel(A));  % the index vectors
B=A.';                              % row major order 'cuz can't write A(:).'
>> fmt=[repmat('%3d,',1,2) '%3d\n']
fmt =
%3d,%3d,%3d\n
>> fprintf(fmt,[i' j' B(:)].')
1,  1,  1
2,  1,  2
3,  1,  3
1,  2,  4
2,  2,  5
3,  2,  6
1,  3,  7
2,  3,  8
3,  3,  9
>>

Let's see about dlmwrite; I don't use it much...

>> dlmwrite('test.txt',[i' j' B(:)],'delimiter',',','precision','%3d')
>> type test.txt
1,  1,  1
2,  1,  2
3,  1,  3
1,  2,  4
2,  2,  5
3,  2,  6
1,  3,  7
2,  3,  8
3,  3,  9

OK, that's ok, too...

BTW, my A was

A=reshape(1:9,3,3).';

just a little different than your example.

Related Solutions

MATLAB: Reading big textfile with textscan

Solution One

You do not need to delete the first ten rows from the file, because textscan has an option to ignore header lines, so you can use this instead:

Out = textscan(....,'HeaderLines',10);

To read 1280 columns of data you need to define this in the format string, so the final code could be something like this:

fmt = repmat('%f',1,1280);
fid = fopen('textfile.txt','rt')
out = textscan(fid, fmt, 'Delimiter',',', 'HeaderLines',10);
fclose(fid);

Solution Two

If the data in the matrix is all numeric (note the header lines do not need to be) then you could use the much simpler dlmread instead, something a bit like this:

out = dlmread('textfile.txt',',',10,0);

Examples

% textscan
fmt = repmat('%f',1,5);
fid = fopen('temp.txt','rt');
out_txt = textscan(fid, fmt, 'Delimiter',',', 'HeaderLines',3);
fclose(fid);
out_txt = cell2mat(out_txt)
% dlmread
out_dlm = dlmread('temp.txt',',',3,0)

display this in the command window:

out_txt =
     0     1     2     3     4
     5     6     7     8     9
out_dlm =
     0     1     2     3     4
     5     6     7     8     9

The sample text file that I used is attached here:

MATLAB: Replacement of groups of neighbor numbers giving priority to a row-wise check

Use the same method as in your previous question except now use the height of the bounding box instead of the area:

m = [2,  2,  2,  2,  2,  2,  2,  2,  2,  2;
     2,  1,  2,  2,  1,  2,  2,  2,  2,  2;
     2,  2,  1,  2,  1,  2,  1,  2,  2,  2;
     2,  2,  1,  2,  2,  2,  1,  2,  2,  2;
     2,  2,  1,  2,  1,  2,  1,  1,  1,  1;
     2,  1,  1,  2,  1,  2,  2,  2,  2,  2;
     2,  1,  2,  2,  1,  2,  2,  2,  2,  2;
     2,  1,  2,  2,  2,  2,  2,  2,  2,  2;
     2,  2,  1,  2,  2,  2,  2,  2,  2,  2;
     2,  2,  2,  2,  2,  2,  2,  2,  2,  2 ]
threshold = 4;
cc = regionprops(logical(2-m), {'BoundingBox', 'PixelIdxList'});
bbox = vertcat(cc.BoundingBox);  %bbox(:, 3) is the width, bbox(:, 4) is the height
m(vertcat(cc(bbox(:, 4) >= threshold).PixelIdxList)) = 2

Best Answer

Related Solutions

MATLAB: Reading big textfile with textscan

MATLAB: Replacement of groups of neighbor numbers giving priority to a row-wise check

Related Question