Write Cell Array of Strings to Text Document

I tried the following code:

fid = fopen('test.txt','wt');

fprintf(fid,'Data:\n');

myCell = {'A','B','C';'D','E','F'};

formatString = [repmat('%s\t',1,size(myCell,2)-1), '%s\n'];

cellfun(@(x) fprintf(fid,formatString,x),myCell.');

fclose(fid);

expecting to get an array printed out, but instead get:

Data:
A  B  C  D  E  F

(there's a newline between the colon and letters, html issue)

Just wondering what I'm doing wrong. I can get it to work using a matrix of numbers instead of strings. Tried dlmwrite too. Although that works for THIS example, it does not work on a more complicated array that I am actually working on (still a cell array of strings though. enough comments warned away from DLMWRITE that I abandoned that path).

Answer 1

[Geoff Hayes]

John - your formatString is initialized as

 formatString =
     %s\t%s\t%s\n

So it is expecting three string inputs but your cellfun function input parameter is only providing one to fprintf

 @(x) fprintf(fid,formatString,x)

If you change this to

 @(x) fprintf(fid,formatString,x,x,x)

and re-run your code, you will see the file contents has been updated to

 Data:
 A  A  A
 B  B  B
 C  C  C
 D  D  D
 E  E  E
 F  F  F

Is this the array that you are expecting?

[John]

Thanks for the help, and that is closer, but what I'm trying to get it just myCell itself, so:

Data:

A B C

D E F

[Geoff Hayes]

In that case, you may want to arrayfun instead and operate on each row of myCell instead of each element within the cell array. Try the following

 fid = fopen('test.txt','wt');
 fprintf(fid,'Data:\n');
 myCell = {'A','B','C';'D','E','F'};
 formatString = [repmat('%s\t',1,size(myCell,2)-1), '%s\n'];
 arrayfun(@(row)fprintf(fid,formatString,myCell{row,:}),1:size(myCell,1));
 fclose(fid);

So the only difference is the arrayfun versus the cellfun. Note how we use myCell in the function that writes each row of the cell array to file. Since we want to write out each row, then we need to specify this using 1:size(myCell,1) which is just an array corresponding to each of the rows. (In this example, the array would be [1 2].)

Running the above code writes the following to your text file

 Data:
 A  B  C
 D  E  F