MATLAB: Vertical alignment with different size character with fprintf.

fprintf

C = {'p.1001',100.500,250.350,;'102',110.550,255.220;'m285',115.210,266.333};
fileID = fopen('celldata.dat','w');
formatSpec = '%s %15.3f %15.3f\n';
[nrows,ncols] = size(C);
for row = 1:nrows
fprintf(fileID,formatSpec,C{row,:});
 end
 fclose(fileID);
% in this case second and third columns cannot be vertically aligned in the text file because first columns' characters are different size. When I use tab (/t), the situation is still same. Is there any way to vertically align 2rd and 3rd columns as independently the 1st columns' characters size?

Best Answer

According to the fprintf documentation one can specify a field width for character substring:
>> fprintf('%s\n','cat')
cat
>> fprintf('%8s\n','cat')
     cat
So simply changing the format string to this will allign all of the columns:
>> formatSpec = '%6s %15.3f %15.3f\n';
If the maximum string width is not known, then you can generate this from the substrings themselves:
>> X = max(cellfun('length',C(:,1)));
>> formatSpec = sprintf('%%%ds %%15.3f %%15.3f\n',X);
Or use this value directly using the * notation:
>> X = max(cellfun('length',C(:,1)));
>> formatSpec = '%*s %15.3f %15.3f\n';
and then
fprintf(fileID, formatSpec, X, C{row,:});
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