Class CloseMatch

source code

   object --+        
            |        
ParserElement --+    
                |    
            Token --+
                    |
                   CloseMatch

A variation on :class:`Literal` which matches "close" matches, that is, strings with at most 'n' mismatching characters. :class:`CloseMatch` takes parameters:

• ``match_string`` - string to be matched
• ``maxMismatches`` - (``default=1``) maximum number of mismatches allowed to count as a match

The results from a successful parse will contain the matched text from the input string and the following named results:

• ``mismatches`` - a list of the positions within the match_string where mismatches were found
• ``original`` - the original match_string used to compare against the input string

If ``mismatches`` is an empty list, then the match was an exact match.

Example:

   patt = CloseMatch("ATCATCGAATGGA")
   patt.parseString("ATCATCGAAXGGA") # -> (['ATCATCGAAXGGA'], {'mismatches': [[9]], 'original': ['ATCATCGAATGGA']})
   patt.parseString("ATCAXCGAAXGGA") # -> Exception: Expected 'ATCATCGAATGGA' (with up to 1 mismatches) (at char 0), (line:1, col:1)

   # exact match
   patt.parseString("ATCATCGAATGGA") # -> (['ATCATCGAATGGA'], {'mismatches': [[]], 'original': ['ATCATCGAATGGA']})

   # close match allowing up to 2 mismatches
   patt = CloseMatch("ATCATCGAATGGA", maxMismatches=2)
   patt.parseString("ATCAXCGAAXGGA") # -> (['ATCAXCGAAXGGA'], {'mismatches': [[4, 9]], 'original': ['ATCATCGAATGGA']})