Turn off global flag in regex [duplicate]

I want to get the first match of a regex.

In this case, I got a list:

text = 'aa33bbb44'
re.findall('\d+',text)

['33', '44']

I could extract the first element of the list:

text = 'aa33bbb44'
re.findall('\d+',text)[0]

'33'

But that only works if there is at least one match, otherwise I'll get an error:

text = 'aazzzbbb'
re.findall('\d+',text)[0]

IndexError: list index out of range

In which case I could define a function:

def return_first_match(text):
    try:
        result = re.findall('\d+',text)[0]
    except Exception, IndexError:
        result = ''
    return result

Is there a way of obtaining that result without defining a new function?

You could embed the '' default in your regex by adding |$:

>>> re.findall('\d+|$', 'aa33bbb44')[0]
'33'
>>> re.findall('\d+|$', 'aazzzbbb')[0]
''
>>> re.findall('\d+|$', '')[0]
''

Also works with re.search pointed out by others:

>>> re.search('\d+|$', 'aa33bbb44').group()
'33'
>>> re.search('\d+|$', 'aazzzbbb').group()
''
>>> re.search('\d+|$', '').group()
''

If you only need the first match, then use re.search instead of re.findall:

>>> m = re.search('\d+', 'aa33bbb44')
>>> m.group()
'33'
>>> m = re.search('\d+', 'aazzzbbb')
>>> m.group()
Traceback (most recent call last):
  File "<pyshell#281>", line 1, in <module>
    m.group()
AttributeError: 'NoneType' object has no attribute 'group'

Then you can use m as a checking condition as:

>>> m = re.search('\d+', 'aa33bbb44')
>>> if m:
        print('First number found = {}'.format(m.group()))
    else:
        print('Not Found')


First number found = 33

Turn off global flag in regex [duplicate]

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