How to print an array with same column starting locations?

I have an array with varying size data values:

A = [ 1.1    2.123    3.12
      1      45.1234  567
      1.23   -3.1     7.34567]

I would like to print the array to a file so that it displays with a flush column starting location as shown. I don't mind going line by line through a for loop, but the size of the array is open to variance, so I cannot go manually line by line.

I have tried using %f designation within fprintf, but this fixes the location of the decimal rather than the first character. I have also tried %e and %g as I don't mind having extra zeroes at the end, however, these two do not properly account for the negative value as shown below.

 for I = 1:3 
     fprintf(file,'%1.6e   %1.6e   %1.6e\n',A(I,:));
end

    1.100000e+00   2.123000e+00   3.120000e+00
    1.000000e+00   4.512340e+01   5.670000e+02
    1.230000e+00   -3.100000e+00   7.345670e+00

Is there some command other than fprintf which can perform this output, or is there some setting within fprintf which can produce the consistent column locations I would like?

Answer 1

[Jos (10584)]

Something like this? You can specify left alignment using the - sign

fprintf([repmat('%-12.4f',1,size(A,2)) '\n'], A.') % note the transpose

[Bob Thompson]

Ok, yes, this gives what I'm looking for, but I want to make sure I understand what it is doing. I'm assuming repmat means "represent matrix" where each value is a floating number with twelve spaces and four decimal spaces (%12.4f). You indicate that the - sign (%-12.4f) causes an alignment left.

What do the 1 and 2 mean, and why does the array need to be transposed? Also, how would I go about doing something like this with a single line from the array?

[Jos (10584)]

The '%-12.4f' is a format specifier for fprintf, meaning that it will take a number, print it using 12 positions, aligned to the left ('-') and with 4 decimal positions.

All the other things are just tricks to make it a one-liner. For readability you could consider a double for loop:

for r = 1:size(A,1) % loop over rows
   for c = 1:size(A,2) % loop over columns
      fprintf('%-12.4f', A(r,c)) ; % print single element
   end
   fprintf('\n') ; % new line after each row
end

repmat means REPeat MATrix.