由于组本身是一个完整的正则表达式，所以可以将组嵌套在其他组中，以构建更复杂的表达式。下面的例子，就是进行组嵌套的例子：
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#python 3.6
#蔡军生
#http://blog.csdn.net/caimouse/article/details/51749579
#
import re
def test_patterns(text, patterns):
"""Given source text and a list of patterns, look for
matches for each pattern within the text and print
them to stdout.
"""
# Look for each pattern in the text and print the results
for pattern, desc in patterns:
print('{!r} ({})\n'.format(pattern, desc))
print(' {!r}'.format(text))
for match in re.finditer(pattern, text):
s = match.start()
e = match.end()
prefix = ' ' * (s)
print(
' {}{!r}{} '.format(prefix,
text[s:e],
' ' * (len(text) - e)),
end=' ',
)
print(match.groups())
if match.groupdict():
print('{}{}'.format(
' ' * (len(text) - s),
match.groupdict()),
)
print()
return
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例子：
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#python 3.6
#蔡军生
#http://blog.csdn.net/caimouse/article/details/51749579
#
from re_test_patterns_groups import test_patterns
test_patterns(
'abbaabbba',
[(r'a((a*)(b*))', 'a followed by 0-n a and 0-n b')],
)
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结果输出如下：
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'a((a*)(b*))' (a followed by 0-n a and 0-n b)
'abbaabbba'
'abb' ('bb', '', 'bb')
'aabbb' ('abbb', 'a', 'bbb')
'a' ('', '', '')
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原文链接：http://blog.csdn.net/caimouse/article/details/78321534