Question

Here is the pattern

pattern_strings = ['\\xc2d', '\\xa0', '\\xe7', '\\xc3\\ufffdd', '\\xc2\\xa0', '\\xc3\\xa7', '\\xa0\\xa0', '\\xc2', '\\xe9']
join_pattern =  '[' + '|'.join(pattern_strings) + ']'
pattern = re.compile(join_pattern)

Here is the function

def find_pattern(path):
    with open(path, 'r') as f:
        for line in f:
            # print line
            found = pattern.search(line)
            if found:
                print dir(found)
                logging.info('found in line - ' + line)
                logging.info('found - ' + str(found.group(0)))

Here is the input

\xc2d 
d\xa0 
\xe7 
\xc3\ufffdd 
\xc3\ufffdd 
\xc2\xa0 
\xc3\xa7 
\xa0\xa0 
'619d813\xa03697' 

When I run this, I get output as

INFO:root:found in line - \xc2d 

INFO:root:found - d
INFO:root:found in line - d\xa0 

INFO:root:found - d
INFO:root:found in line - \xc3\ufffdd 

INFO:root:found - u
INFO:root:found in line - \xc3\ufffdd 

INFO:root:found - u
INFO:root:found in line - '619d813\xa03697' 

INFO:root:found - d

Question
– Why doesn’t it tells the entire pattern like \xc2d? am I doing something incorrect here?
– What is that I need to do in order to get the pattern matched like \xc2d instead of d

UPDATE

chaging to join_pattern = '(' + '|'.join(pattern_strings) + ')' doesn’t matches anything

UPDATE 1

pattern_strings = ['\\xc2d', '\\xa0', '\\xe7', '\\xc3\\ufffdd', '\\xc2\\xa0', '\\xc3\\xa7', '\\xa0\\xa0', '\\xc2', '\\xe9']

join_pattern =   '|'.join(pattern_strings)
pattern = re.compile(join_pattern)

This doesn’t matches anything in input 🙁

Answer 1

Square brackets in re denotes a set

join_pattern = '[' + '|'.join(pattern_strings) + ']' causes the regex to match “any one of the set of characters in { \ x c 2 d a 0 e 7 3 u f 9 | }“. This is probably not the behavior you want. For the expression you want just use:

join_pattern = '|'.join(pattern_strings)

No need for parentheses, unlesss you are trying to specify capture/non-capture groups.