> from urllib import parse
> url = 'http://www.baidu.com/s?wd=codeif.com&spt=1'
> bits = list(parse.urlparse(url))
> bits
['http', 'www.baidu.com', '/s', '', 'wd=codeif.com&spt=1', '']
> qs = parse.parse_qs(bits[4])
> qs
{'wd': ['codeif.com'], 'spt': ['1']}
> qs['wd'] = ['sina','@www']
> qs['pg'] = [8]
> del qs['spt']
> qs
{'pg': [8], 'wd': ['sina', '@www']}
> bits[4] = parse.urlencode(qs, True)
> bits
['http', 'www.baidu.com', '/s', '', 'pg=8&wd=minicn&wd=%40www', '']
> url = parse.urlunparse(bits)
> url
'http://www.baidu.com/s?pg=8&wd=minicn&wd=%40www'
>