Dynamic formatting of strings in Matlab

Question

I'm trying to write a Matlab program that takes an input from the user for the number of rows to be displayed and accordingly prints something like :

1
2 2
3 3 3

.. so on

Now I could get this output using two for loops, but is it possible to do the same with one for loop? Specifically, I'd like to know if there's a way by which we could pass the iteration value of the for loop to the sprintf/fprintf statement to format the string in a way similar to '%3d' so that the sprintf/fprintf statement knows how many variables are to be printed on each line. Hope that wasn't too messy.

Thank you!

Shantanu.

PearsonArtPhoto · Accepted Answer · 2012-12-19 15:20:57Z

2

You could simply create an array each pass through to the appropriate size, like this:

fid=1; % Will print out to the stdout, but can replace this with the folder to write to
for x=1:3
   stuff=zeros(x,1)+x;
   fprintf(fid,'%s ',stuff)
   fprintf(fid,'\n');
end

Note that if an array is passed to a fprintf statement, it will simply repeat it until the array is finished.

edited Dec 19, 2012 at 15:20

answered Dec 19, 2012 at 14:45

PearsonArtPhoto

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4 Comments

Shantanu Over a year ago

Thanks for the suggestion. But I'm trying to get this done while writing the output into a file. So I guess the display statement would not work, right?

PearsonArtPhoto Over a year ago

I've come up with an alternative that works, but is a bit harder to explain. To output it to a file, just add the fid as the first argument, and you're set.

Shantanu Over a year ago

Okay, I think I have the answer to what I was looking for. Basically I was unsure if an entire array could be passed to the sprintf/fprintf statement. Turns out, Matlab does permit it. Wait, did you edit your response to include the thing about the array? Yes, that's what I've been looking for. Thanks a ton! :)

Shantanu Over a year ago

Yeah, I'd upvoted your response, though I wasn't aware of accepting. Thanks again.

HericDenis · Accepted Answer · 2012-12-19 15:14:00Z

2

Try sprintf function, here is the documentation. Than you do something like:

sprintf('something %[flag][width].[precision][conversion] %...', arg1, ...)

for integer decimals you can just do:

sprintf('%d', integer)

edited Dec 19, 2012 at 15:14

answered Dec 19, 2012 at 14:47

HericDenis

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2 Comments

H.Muster Over a year ago

The usage of disp and sprintf together is redundant; using the latter is sufficient, says Matlab.

HericDenis Over a year ago

@H.Muster, updated my answer, some time no use MatLab forgot that.

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