Strings and numbers, strcat and num2str

I'm working with SDSS data and want to get rid of some fits files from the ones I have downloaded. I have stored the pl #, mjd, fb # in respective variables and the format of SDSS file naming is spec-plate-mjd-fiber.fits where

• plate ranges from 250-3500
• mjd is always 5 digits
• fiber is 1-640.

I want to concatenate the plate, mjd and fiber number to check for the files and exclude/move them. Here's my code

Tz = '-000'; tz = '-00'; oz = '-0'; j=1;
for j=1:length(pl)
 if and(pl(j) < 999, fb(j) < 10)
     b = ['spec-0', num2str(pl(j)), '-', num2str(mj(j)), Tz, num2str(fb(j))];
 end
 if and(pl(j) < 999, or(fb(j) >= 10, fb(j) < 100))
     b = ['spec-0', num2str(pl(j)), '-', num2str(mj(j)), tz, num2str(fb(j))];
 end
 if and(pl(j) < 999, or(fb(j) >= 100, fb(j) < max(fb)))
     b = ['spec-0', num2str(pl(j)), '-', num2str(mj(j)), oz, num2str(fb(j))];
 end
 if and(pl(j) >= 1000, fb(j) < 10)
     b = ['spec-', num2str(pl(j)), '-', num2str(mj(j)), Tz, num2str(fb(j))];
 end
 if and(pl(j) >= 1000, or(fb(j) >= 10, fb(j) < 100))
     b = ['spec-', num2str(pl(j)), '-', num2str(mj(j)), tz, num2str(fb(j))];
 end
 if and(pl(j) >= 1000, or(fb(j) >= 100, fb(j) < max(fb)))
     b = ['spec-', num2str(pl(j)), '-', num2str(mj(j)), oz, num2str(fb(j))];
 end
 c{j} = b;
end

The problem is with fb < 100, it gives spec-1835-54563-077 instead of spec-1835-54563-0077 and same with fb < 10. How can I solve this?

[Stephen23]

Note that the concatenations and multiple num2str should be replaced with one sprintf:

 b = ['spec-0', num2str(pl(j)), '-', num2str(mj(j)), oz, num2str(fb(j))];
 % vs.
 b = sprintf('spec-0%f-%f%s%f',pl(j),mj(j),oz,fb(j));

[Syed Ali Mohsin Bukhari]

oz wasn't needed that much. I just initialized it because I was too lazy to write -0 again and again, same with Tz and tz, but yes by using sprintf my problem got solved. Thank you .

Answer 1

[James Tursa]

Is this what you want?

b = sprintf('spec-%04d-%05d-%04d',pl(j),mj(j),fb(j));

[Syed Ali Mohsin Bukhari]

You shrank the code, a little too much. Thank you, this did the trick.