How to convert and write nested cell arrays into a TXT file without adding extra quotes?

Hello everyone,

I wanted to convert a (293 x 1) cell containing only one datatype (string) into a TXT file. The TXT file should look exactly like the plane.mat file without any additional " " quotes. I wanted to achieve this with the following command:

writecell(CATIA_EBENE_MAKRO, 'Test.txt')    

However once I open the TXT file I have some issues with the representation:

1.) I do not know how to get rid of the additional " " quotes from the string data type

2.) In some lines the " " quotes are strangely adding up by one in the TXT file compared to the original plane.mat file:

'Set hybridShapeSpline11= hybridShapes1.Item("Spline.1")'     % e.g 11th row of the 293 x 1 cell in the plane.met file

"'Set hybridShapeSpline11= hybridShapes1.Item(""Spline.1"")'"  % e.g 11th in the TXT File after the conversion

% Notice: The "Spline.1" is intended. It just bother me that after that the TXT file (after conversion) shows ""Spline.1""  

So I would like to ask you if I could, e.g with the cellfun command, get rid of the outer " " quotes as well as solve the problem with the "" "" double quotes? Since I am not familiar with the data export to a different file I would like to ask you if you have a code in mind?

Answer 1

[David Jacob]

Hey,

You can use fopen() and fprintf() for that.

1. Open your the file you want to write to in writing mode: f=fopen('Test.txt','w')
2. Add each row of that cell array as a string to your file: fprintf(f,'%s\n',CATIA_EBENE_MAKRO{:})
3. Make sure to close the file: fclose(f)

[David Mrozek]

Ok this helped me a lot. But for a better better learning experience I would like to ask you about your thought process behind it (if you don´t mind)?

a.) I do not understand the 'w' after fopen in point 1.)

Is this a condition under which the txt file should be opened??

b.) In your 2nd point there is the string '%s\n', Does the % sign have another purpose expect being

the indicator for a comment? This goes also for the s and \n signs?

I have seen this sign at some other websites but I cannot imagine their usage...

Anyway thank you very much!!!

[David Jacob]

The 'w' specifies the file access type of the fopen() function. By default fopen() opens a file for reading. That's why I specified 'w' to write to the file. Once opened the file remains open in MATLAB until you close it using fclose().

Within the fprintf() function I used a formating operator (%). I put %s to add the strings inside your array.

Use \n in order to go to the next row, once a row is finished. That way you prevent that all your cell elements are going to be printed into the same row in your text file.

The : operator at the end of at the end of your cell array works like a for loop that goes through your cell array and prints each cell array at the position of your place holder %s.

I hope that makes it a little clearer. Let me know if you have any questions left! Also, check out the MATLAB documentation on the fopen() and fprintf() functions.

[David Mrozek]

Yes, it was very detailed! Thanks

[Rik]

Just a clarifying note:

data{:}

will generate a comma separated list. In the fprintf call it would be equivalent of doing this (assuming data is a 3 element array):

fprintf('%s\n',data{1},data{2},data{3})

You can also use this in other circumstances, like cat. I also sometimes use it to generate multidimentional arrays:

A=cell(1,3);
[A{:}]=ndgrid(1:3);
celldisp(A)

 
A{1} =
 

(:,:,1) =

     1     1     1
     2     2     2
     3     3     3


(:,:,2) =

     1     1     1
     2     2     2
     3     3     3


(:,:,3) =

     1     1     1
     2     2     2
     3     3     3

 
 
A{2} =
 

(:,:,1) =

     1     2     3
     1     2     3
     1     2     3


(:,:,2) =

     1     2     3
     1     2     3
     1     2     3


(:,:,3) =

     1     2     3
     1     2     3
     1     2     3

 
 
A{3} =
 

(:,:,1) =

     1     1     1
     1     1     1
     1     1     1


(:,:,2) =

     2     2     2
     2     2     2
     2     2     2


(:,:,3) =

     3     3     3
     3     3     3
     3     3     3

 

And I absolutely agree with the advice to read the documentation. It is one of the major advantages of Matlab over the competition.

[Stephen23]

Prefer to open the file in text mode too, which will neatly handle the EOL conversion for your OS:

fid = fopen('Test.txt','wt')
%                        ^ text mode

Useful information on comma-separated lists:

https://www.mathworks.com/help/matlab/matlab_prog/comma-separated-lists.html

https://www.mathworks.com/matlabcentral/answers/320713-how-to-operate-on-comma-separated-lists