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file name manipulation

Asked by Jason
on 6 May 2011

I have a file name that takes the form: S_1_X_Y where X can be an integer between 1-16, and Y is a letter a,b,c,d.

I want to be able to just replace the number X by a user defined value.

any help greatly appreciated. Thanks

  1 Comment

Just to add, the "1" in the file name can also be 1,2,3,4.

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2 Answers

Answer by Oleg Komarov on 6 May 2011
 Accepted Answer

X = 1;
Y = 'a';


str = 'S_1_6_a'
x   = 3;
regexprep(str,'(_)\d+(_[abcd])', ['$1' sprintf('%d',x) '$2'])
ans =


Show 1 older comment

I misread your request at first, now given a string name "str", it replaces the 6 in the example with the number 3.

but sometimes the number to be replaced can be single digit 1-9) or double digit 10-16.

sorry, i didn't realise you code handles this. Thanks

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Answer by Teja Muppirala
on 6 May 2011

NUM2STR is useful for stuff like this.

Y = {'a' 'b' 'c' 'd'}
for jj = 1:4
  for n = 1:9
    filename = ['S_1_' num2str(n) '_' Y{jj}]

Or alternatively, if you need to have zeros in there like '001', '002', '003' then you can use SPRINTF instead of NUM2STR

n = 7;
filename = ['S_1_' sprintf('%03.f',n) '_a']
n = 61;
filename = ['S_1_' sprintf('%03.f',n) '_a']


num2str supports the format:

sorry, I didn't explain my question clearly. I read in a filename that takes the form S_1_X_Y e.g. S_1_6_a the "a" character can be either a,b,c,d. X can be 1 to 16..

Once this filename is read in as a string, I need to keep it exactly the same, but only change the character X to a different number between 1-16.

I edited my answer. Check it out.

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