string - num2str auto width format in MATLAB

Question

Sorry for my dumb question, i'm new on matlab. I have an matrix array like this

num = [
    4.2, 3, 5;
    3, 12.1, 3.4;
    2, 5.22, 4
]

I just want to display it using center align format, like the example below

but number in num array is dynamic, sometimes on each row contain up to 4 or more number like this

num = [
    4.2, 3, 5, 7.899;
    3, 12.1, 3.4, 89;
    2, 5.22, 4, 9.1
]

I was trying using num2str() function, but it doesn't fit on my case because my data is dynamic (sometimes it always have 2 or 3 more digit of decimal number) here is my code:

num2str('%10.1f \t %10.1f \t %10.1f \n', num);

Is there any other function beside using num2str(), because my array data is dynamic

Answer 1

You can centre a string with strjust. Here, I build the individual elements in a loop with sprintf and add a newline character:

num = [
4.2, 3, 5, 7.899;
3, 12.1, 3.4, 89;
2, 5.22, 4, 9.1
];

% Loop over rows (ii) and columns (jj) of num
output = '';
for ii = 1:size(num,1)
  for jj = 1:size(num,2)
    output = [output, strjust(sprintf('%10.4g',num(ii,jj)),'center')];
  end % for jj
  output = [output, '\n'];
end % for ii
fprintf(output)

Output:

   4.2        3         5       7.899   
    3        12.1      3.4        89    
    2        5.22       4        9.1    

You can put this into e.g. an image by using a final call to sprintf:

text(0.5, 0.5, sprintf(output))

Note that this uses a non-fixed width font, so a long line might not look centre-justified. This can be seen by using

num = [999, 999, 999, 999; 1, 1, 1, 1];

MATLAB version R2014a.