How to extract only alphabets from mixed string

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Hi,
I have a mixed string as below:
string=BA9K90L
And I only want to extract alphabets i.e., BAKL. Kindly some one help how can we do this.
Many thanks in advance,

Accepted Answer

Stephen23
Stephen23 on 26 Mar 2016
This is easy using the inbuilt isstrprop function:
>> S = 'BA9K90L';
>> S(isstrprop(S,'alpha'))
ans =
BAKL

More Answers (1)

Ced
Ced on 26 Mar 2016
Edited: Ced on 26 Mar 2016
Hi
You can use fancy functions like regexp or so, but this is my suggestion:
str = 'BA9K90L';
% pick out letters only (using ASCII value)
str = str(double(str) > 64)
Done! :)
Cheers
EDIT: This does not work if you have more than alphanumeric strings, see Stephen's answer for a complete check.
  5 Comments
Guillaume
Guillaume on 26 Mar 2016
I totally agree with Stephen. Correct and obvious code trumps fast code. While comparing to 'A' (and that would have been clearer than comparing to 64) works in the toy example provided, it certainly is not robust.
There are tons of characters (>120,000 in the unicode standard) above 64 that may or may not be alphabetic. isstrprop at least attempts to do the right thing and takes into account the current locale.
Ced
Ced on 26 Mar 2016
Edited: Ced on 26 Mar 2016
@Guillaume:
Of course. I admit that I understood the question as "if I have a string with letters and numbers, how to I extract the letters", as this was given in the example. I have no problem admitting the correctness of his solution, and it was good to point out the limitation. That being said, I see this forum as a place where people share ideas and solutions, and not one of industrial competition. Even Dr. Siva's answer, while being unnecessarily long, is a contribution. It's up to the OP to decide which answer suits their need.
Anyway, that is irrelevant for the topic at hand.

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