MATLAB: Using fprintf to print in text file

Question

Hi all,

I'm very very unfamiliar with MATLAB. I've been trying to write a code that can neatly organize the data that is stored in certain variables into a text file.

What I want the final product to look like is this:

Each column is stored in separate variables (e.g. nodeID=[1;2;3;4], X=[0;0;120;120], etc)

I've been trying to use frpintf function and got to where there is a breakline between the column titles and the numbers.

I'd like to know how to evenly space these numbers as shown in the picture. Currently I've been adding spaces (using ' ') via fprintf but this gives me something that looks like below:

the code i have is the following (it's embarrassing really):

here nNode = 4,

for i = 1:nNode

fprintf(txt,'\n');

fprintf(txt, '%d', nodeID(i));

fprintf(txt, ' ');

fprintf(txt, '%.2f', X(i));

fprintf(txt, ' ');

fprintf(txt, '%.2f', Y(i));

fprintf(txt, ' ');

fprintf(txt, '%.3f', fx(i));

fprintf(txt, ' ');

fprintf(txt, '%.3f', fy(i));

end

Is there a more efficient way to go about this issue?

Thanks a bunch 🙂

Answer 1

Hey Sung,

Instead of printing a fixed number of spaces with ' ', you may set the total width of your value in the format string like this:

sprintf('%10.2f %10.2f', 120, 120) %Each value of 120 is displayed with total width 10 and precision 2.

Use '%w.2f' to set the width of the display value to 'w', which would fill in empty spaces as required.

This would align values in a column on the rightmost digit.

[I used 'w' to illustrate only. You can't use a variable this way, you will need to replace 'w' with your required number, say '%15.2f' or '%20.2f']

[sprintf and fprintf both work the same way, I used sprintf just to demonstrate]

Hope it helps!