>>> import re
>>> s = 'gctagcta'
>>> expr = '[gcta]+'
>>> re.findall(expr, s)
Out[1]: ['gctagcta']
>>> s = 'GGgctagcXta???'
>>> re.findall(expr, s)
Out[1]: ['gctagc', 'ta']
>>> expr = '[gGcCtTaA]+'
>>> re.findall(expr, s)
Out[1]: ['GGgctagc', 'ta']


>>> s = '11gctagcxta???'
>>> expr = '[a-z0-9_]+'
>>> re.findall(expr, s)
Out[1]: ['11gctagcxta']
>>> expr = '[0-9]+[a-z0-9_]*'
>>> re.findall(expr, s)
Out[1]: ['11gctagcxta']
>>> expr = '[a-z]+[a-z0-9_]*'
>>> re.findall(expr, s)
Out[1]: ['gctagcxta']
>>> expr = '^[a-z]+[a-z0-9_]*$'
>>> re.findall(expr, s)
Out[1]: []
>>> expr = '^[0-9]+[a-z0-9_]*$'
>>> re.findall(expr, s)
Out[1]: []
>>> s = '11gctagcxta000'
>>> re.findall(expr, s)
Out[1]: ['11gctagcxta000']
>>> expr = '^[0-9]+.*[0-9]+$'
>>> re.findall(expr, s)
Out[1]: ['11gctagcxta000']
>>> s = '11gctag????<><)(^^%%%$##DSFDKUYGFUQYGEYFAScxta000'
>>> re.findall(expr, s)
Out[1]: ['11gctag????<><)(^^%%%$##DSFDKUYGFUQYGEYFAScxta000']


>>> numPatt = '^[+-]?[0-9]*\.?[0-9]+$'
>>> re.findall(numPatt, '1')
Out[1]: ['1']
>>> numPatt = '^[+-]?[0-9]*\\.?[0-9]+$'
>>> re.findall(numPatt, '1')
Out[1]: ['1']
>>> numPatt = r'^[+-]?[0-9]*\.?[0-9]+$'
>>> re.findall(numPatt, '1')
Out[1]: ['1']
>>> re.findall(numPatt, '-1')
Out[1]: ['-1']
>>> re.findall(numPatt, '-1.1')
Out[1]: ['-1.1']
>>> re.findall(numPatt, '-.1')
Out[1]: ['-.1']
>>> re.findall(numPatt, '+31')
Out[1]: ['+31']
>>> re.findall(numPatt, 'a')
Out[1]: []
>>> re.findall(numPatt, '--1')
Out[1]: []
>>> re.findall(numPatt, '-1..1')
Out[1]: []
>>> re.findall(numPatt, '-1.3.1')
Out[1]: []
>>> re.findall(numPatt, '-1a')
Out[1]: []
>>> numPatt = r'^[+-]?[0-9]*\.?[0-9]+'
>>> re.findall(numPatt, '-1a')
Out[1]: ['-1']
>>> numPatt = r'^[+-]?[0-9]*\.?[0-9]+$'
>>> re.findall(numPatt, '-1a1')
Out[1]: []
>>> numPatt = r'[+-]?[0-9]*\.?[0-9]+'
>>> re.findall(numPatt, '-1a1')
Out[1]: ['-1', '1']
>>> numPatt = r'[+-]?[0-9]*[\.,]?[0-9]+'
>>> re.findall(numPatt, '-1.1')
Out[1]: ['-1.1']
>>> re.findall(numPatt, '-1,1')
Out[1]: ['-1,1']
>>> numPatt = r'^[+-]?\d*\.?\d+$'
>>> re.findall(numPatt, '-1.1')
Out[1]: ['-1.1']
>>> re.findall('\w+', 'AbcD')
Out[1]: ['AbcD']
>>> re.findall('[\w\d]+', 'AbcD')
Out[1]: ['AbcD']
>>> re.findall('[\w\d]+', 'AbcD123')
Out[1]: ['AbcD123']
>>> re.findall('[\w\d]+', 'AbcD123')
Out[1]: ['AbcD123']

>>> numPatt = r'^([+-]?\d*)\.?(\d+)$'
>>> re.findall(numPatt, '-1.1')
Out[1]: [('-1', '1')]


>>> phonePatt = '(\d+)-(\d+)-(\d+)'
>>> re.findall(phonePatt, '800-555-1212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '800 555 1212')
Out[1]: []
>>> phonePatt = '(\d+)-(\d+)-(\d+)'
>>> re.findall(phonePatt, '8005551212')
Out[1]: []
>>> phonePatt = '(\d+)-?(\d+)-?(\d+)'
>>> re.findall(phonePatt, '8005551212')
Out[1]: [('80055512', '1', '2')]
>>> phonePatt = '(\d\d\d)-?(\d\d\d)-?(\d\d\d\d)'
>>> re.findall(phonePatt, '8005551212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '800-555-1212')
Out[1]: [('800', '555', '1212')]
>>> phonePatt = '(\d{3})-?(\d{3})-?(\d{4})'
>>> re.findall(phonePatt, '800-555-1212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '8005551212')
Out[1]: [('800', '555', '1212')]
>>> phonePatt = '(\d{3})_?-?(\d{3})_?-?(\d{4})'
>>> re.findall(phonePatt, '800 555 1212')
Out[1]: []
>>> phonePatt = '(\d{3})\ -?(\d{3})\ -?(\d{4})'
>>> re.findall(phonePatt, '800 555 1212')
Out[1]: [('800', '555', '1212')]
>>> phonePatt = '(\d{3})\ ?-?(\d{3})\ ?-?(\d{4})'
>>> re.findall(phonePatt, '800 555 1212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '800-555-1212')
Out[1]: [('800', '555', '1212')]
>>> phonePatt = '(\d{3})[\.\s-]?(\d{3})[\s\.-]?(\d{4})'
>>> re.findall(phonePatt, '800.555.1212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '800 555 1212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '800-555-1212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '8005551212')
Out[1]: [('800', '555', '1212')]
>>> phonePatt = '\(?(\d{3})[\)\.\s-]?(\d{3})[\s\.-]?(\d{4})'
>>> re.findall(phonePatt, '(800)5551212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '(800) 5551212')
Out[1]: []
>>> phonePatt = '\(?(\d{3})\)?\s*[\.-]?\s*(\d{3})\s*[\.-]?\s*(\d{4})'
>>> re.findall(phonePatt, '(800) 5551212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '(800) 555-1212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '(800) 555 - 1212')
Out[1]: [('800', '555', '1212')]
>>> re.findall(phonePatt, '1-800-555-1212')
Out[1]: [('800', '555', '1212')]
>>> phonePatt = '\(?\d{3}\)?\s*[\.-]?\s*\d{3}\s*[\.-]?\s*\d{4}'
>>> re.findall(phonePatt, '1-800-555-1212')
Out[1]: ['800-555-1212']