ktsirig

Hi all!
Suppose you have the following string of letters :

$string ='LPSTEOPRTRYERTRETR';
and you want to search for the following pattern inside the string:
$pattern= LP[SKTAQEHLDN][TA][GN][EDASTV] =>5/6
By saying 5/6, I mean that you can have one mismatch but still it must return success.
If you check the string above, it has L, P, S, T and then E. There is no G in the pattern, but I am ok with it...
So, my question is how can you set a threshold in pattern matching above which you will return success...

DaWei

A match is not qualitative. It's true, or false. You may define "degree of mismatch" however you like. One way to accomplish what you ask (I don't know for sure that it's what you mean) is to conduct the tests serially and determine the ratio of successes to failures. Whether or not the resulting definition of "LIKE" is useful depends on your goals.

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jim mcnamara

You can create "optional" matches. I can't quite understand your example, so I am making my own. Plus you seem to be doing odd things with character classes.

The ? mark denotes an optional numeric character class. This pattern finds "whole variables" that are either 5 or 6 numeric characters long. So, pattern will match string2 and string3.

What exactly are you trying to do? You can get "partial" matches with optional lookaround. The best approach when you have a hashed up situtation in regular expressions is to provide for yourself:

1. a clear set of examples for yourself that both match and do not match.
2. Derive these examples from from your known data universe.
3. Write a clear (English, Dutch, whatever) sentence that sets down what you're trying to do.

Go from there. Test your pattern against a bunch of trial data items.