Python: JavaScript like parseInt function in one line

parseInt.py

#lsauer.com, 2013
#Note: -)for convenience the function uses the re-module, but can be rewritten to fit into a lambda expression
#      -)choose any other, more-expressive return type such as NumPy's `nan` over None if you like

#demonstrative-version:
def parseInt(sin):
  import re
  return int(''.join([c for c in re.split(r'[,.]',str(sin))[0] if c.isdigit()])) if re.match(r'\d+', str(sin), re.M) and not callable(sin) else None

#via a simple regex:
def parseInt(sin):
  import re
  m = re.search(r'^(\d+)[.,]?\d*?', str(sin))
  return int(m.groups()[-1]) if m and not callable(sin) else None
  
#as a lambda function:
parseInt = lambda sin: int(''.join([c for c in str(sin).replace(',','.').split('.')[0] if c.isdigit()])) if sum(map(int,[s.isdigit() for s in str(sin)])) and not callable(sin) and str(sin)[0].isdigit() else None

python_lparseInt.py

#like parseInt but allow potentially parsed numbers to begin-left with a string
#demonstrative-version:
def lparseInt(sin):
  import re
  return int(''.join([c for c in re.split(r'[,.]',str(sin))[0] if c.isdigit()])) if re.findall(r'(\d+)[.,]?\d*?', str(sin), re.M) and not callable(sin) else None

#via a simple regex:
def lparseInt(sin):
  import re
  m = re.search(r'(\d+)[.,]?\d*?', str(sin))
  return int(m.groups()[-1]) if m and not callable(sin) else None
  
#as a lambda function:
lparseInt = lambda sin: int(''.join([c for c in str(sin).replace(',','.').split('.')[0] if c.isdigit()])) if sum(map(int,[s.isdigit() for s in str(sin)])) and not callable(sin) else None

quicktests_parseInt.py

#most useful in combination with map, filter and reduce
map(parseInt, ['', 100, '234324']) #...
#> [None, 100, 234324]...

#tests
parseInt(None)
parseInt(lambda: None)
parseInt('')
parseInt(r'')
parseInt(100)
parseInt(())
parseInt((0,1))
parseInt([])
parseInt(100.23)
parseInt('abcd100,10')
parseInt('100,30')
parseInt('100.30')
parseInt('abcd100,10dddd')
parseInt('abcd100.10dddd')
parseInt('100,10dddd')
parseInt('100.10dddd')
parseInt('1234567890.1234567890')
parseInt('1234567890,1234567890')
parseInt('123456789012345678901234567890123456789012345678901234567890')


_tarr = [19,
 None,
 lambda: None,
 '',
 '',
 100,
 (),
 (0, 1),
 [],
 100.23,
 'abcd100,10',
 '100,30',
 '100.30',
 'abcd100,10dddd',
 'abcd100.10dddd',
 '100,10dddd',
 '100.10dddd',
 '1234567890.1234567890',
 '1234567890,1234567890',
 '123456789012345678901234567890123456789012345678901234567890']

#results:
In[1]: zip(_tarr,map(parseInt,_tarr))
Out[1]: 
[(19, 19),
 (None, None),
 (<function __main__.<lambda>>, None),
 ('', None),
 ('', None),
 (100, 100),
 ((), None),
 ((0, 1), None),
 ([], None),
 (100.23, 100),
 ('abcd100,10', None),
 ('100,30', 100),
 ('100.30', 100),
 ('abcd100,10dddd', None),
 ('abcd100.10dddd', None),
 ('100,10dddd', 100),
 ('100.10dddd', 100),
 ('1234567890.1234567890', 1234567890),
 ('1234567890,1234567890', 1234567890),
 ('123456789012345678901234567890123456789012345678901234567890',
  123456789012345678901234567890123456789012345678901234567890L)]
  
In [2]:zip(_tmp,map(lparseInt,_tmp))
Out[2]: 
[(19, 19),
 (None, None),
 (<function __main__.<lambda>>, None),
 ('', None),
 ('', None),
 (100, 100),
 ((), None),
 ((0, 1), 0), #attention!
 ([], None),
 (100.23, 100),
 ('abcd100,10', 100),
 ('100,30', 100),
 ('100.30', 100),
 ('abcd100,10dddd', 100),
 ('abcd100.10dddd', 100),
 ('100,10dddd', 100),
 ('100.10dddd', 100),
 ('1234567890.1234567890', 1234567890),
 ('1234567890,1234567890', 1234567890),
 ('123456789012345678901234567890123456789012345678901234567890',
  123456789012345678901234567890123456789012345678901234567890L)]

or simpler:

def parseInt(s):
    digits = ''
    for c in str(s).strip():
        if not c.isdigit():
            break
        digits += c

    return int(digits) if digits else None