alphanumeric = compile('^[wd ]+$')

Tomkiewicz Zigomalas Andrade Mcwalters

>>> an_re = r"(d+[A-Z])|([A-Z]+d)[dA-Z]*"
>>> re.search(an_re, '12345', re.I) # not acceptable string
>>> re.search(an_re, 'abcd', re.I) # not acceptable string
>>> re.search(an_re, 'abc1', re.I) # acceptable string
<_sre.SRE_Match object at 0x14153e8>
>>> re.search(an_re, '1abc', re.I)
<_sre.SRE_Match object at 0x14153e8>

(?=.*[a-zA-Z])(?=.*[0-9])^[wd ]+$