python正则表达式复习2

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大小写不区分匹配，使用\b

import retext = 'This is some text -- with punctuation.'# 匹配以T开头的单词pattern = r'\bT\w+'with_case = re.compile(pattern)# 不区分大小写without_case = re.compile(pattern, re.IGNORECASE)print 'Text:\n %r' % textprint 'Pattern:\n %s' % patternprint 'Case-sensitive:'for match in with_case.findall(text):    print ' %r' % matchprint 'Case-insensitive:'for match in without_case.findall(text):    print ' %r' % match

结果
Text:
‘This is some text – with punctuation.’
Pattern:
\bT\w+
Case-sensitive:
‘This’
Case-insensitive:
‘This’
‘text’

多行匹配与单行匹配

text = 'This is some text -- with punctuation.\nA second line.'# 查找开头和结尾的非空白字符pattern = r'(^\w+)|(\w+\S*$)'single_line = re.compile(pattern)# 加上多行匹配，即处理\nmultiline = re.compile(pattern, re.MULTILINE)print 'Text:\n %r' % textprint 'Pattern:\n %s' % patternprint 'Single Line :'for match in single_line.findall(text):    print ' %r' % (match,)print 'Multiline :'for match in multiline.findall(text):    print ' %r' % (match,)

结果
Text:
‘This is some text – with punctuation.\nA second line.’
Pattern:
(^\w+)|(\w+\S*$)
Single Line :
(‘This’, ”)
(”, ‘line.’)
Multiline :
(‘This’, ”)
(”, ‘punctuation.’)
(‘A’, ”)
(”, ‘line.’)
注：多行考虑时，\n后面的字符串被当作另外一行考虑

dotall，点包括了换行符

text = 'This is some text -- with punctuation.\nA second line.'pattern = r'.+'no_newlines = re.compile(pattern)# 默认'.'是不匹配换行符的，加上re.DOTALL标记，即包括换行符dotall = re.compile(pattern, re.DOTALL)print 'Text:\n %r' % textprint 'Pattern:\n %s' % patternfor match in no_newlines.findall(text):    print ' %r' % matchprint 'Dotall :'for match in dotall.findall(text):    print ' %r' % match

结果
Text:
‘This is some text – with punctuation.\nA second line.’
Pattern:
.+
No newlines :
‘This is some text – with punctuation.’
‘A second line.’
Dotall :
‘This is some text – with punctuation.\nA second line.’

unicode匹配，re.UNICODE

import codecsimport sys# 设置标准输出为utf-8格式sys.stdout = codecs.getwriter('UTF-8')(sys.stdout)text = u'Français złoty Österreich'pattern = ur'\w+'ascii_pattern = re.compile(pattern)unicode_pattern = re.compile(pattern, re.UNICODE)print 'Text :', textprint 'Pattern :', patternprint 'ASCII :', u', '.join(ascii_pattern.findall(text))print 'Unicode :', u', '.join(unicode_pattern.findall(text))

结果
Text : Français złoty Österreich
Pattern : \w+
ASCII : Fran, ais, z, oty, sterreich
Unicode : Français, złoty, Österreich
注：在没有加上unicode匹配时，不是ascii码的字符，无法匹配

正则表达式注释，并已json输出

# 匹配某些带尖括号的匹配邮箱address = re.compile(    '''    ((?P<name>    ([\w.,]+\s+)*[\w.,]+) # 名字中可能包含点字符    \s*    < # 当有名字的时候，邮箱是放在尖括号里面的    )? # 邮箱前面的名字可有可无    (?P<email>    [\w\d.+-]+ # 邮箱符号的前面是一个名称    @    ([\w\d.]+\.)+ # 域名的前缀    (com|org|edu) # 限制哪些域名是在考虑范围的    )    >? # 尖括号是根据前面有没有名字而可有可无的    ''',    re.UNICODE | re.VERBOSE)candidates = [    u'first.last@example.com',    u'first.last+category@gmail.com',    u'valid-address@mail.example.com',    u'not-valid@example.foo',    u'First Last <first.last@example.com>',    u'No Brackets first.last@example.com',    u'First Last',    u'First Middle Last <first.last@example.com>',    u'First M. Last <first.last@example.com>',    u'<first.last@example.com>',    ]for candidate in candidates:    print 'Candidate:', candidate    match = address.search(candidate)    if match:        print match.groupdict()    else:        print ' No match'

结果
Candidate: first.last@example.com
{‘name’: None, ‘email’: u’first.last@example.com’}
Candidate: first.last+category@gmail.com
{‘name’: None, ‘email’: u’first.last+category@gmail.com’}
Candidate: valid-address@mail.example.com
{‘name’: None, ‘email’: u’valid-address@mail.example.com’}
Candidate: not-valid@example.foo
No match
Candidate: First Last first.last@example.com
{‘name’: u’First Last’, ‘email’: u’first.last@example.com’}
Candidate: No Brackets first.last@example.com
{‘name’: None, ‘email’: u’first.last@example.com’}
Candidate: First Last
No match
Candidate: First Middle Last first.last@example.com
{‘name’: u’First Middle Last’, ‘email’: u’first.last@example.com’}
Candidate: First M. Last first.last@example.com
{‘name’: u’First M. Last’, ‘email’: u’first.last@example.com’}
Candidate: first.last@example.com
{‘name’: None, ‘email’: u’first.last@example.com’}

注：名字可有可无，因此会出现name为none的情况

通过?i来标记忽略大小写

# 通过加入标签(?i)忽略大小写，其它的标签 IGNORECASE:i,# MULTILINE:m,DOTALL:s,UNICODE:u,VERBOSE:x ,可以同时加入多个标签如:?imutext = 'This is some text -- with punctuation.'pattern = r'(?i)\bT\w+'regex = re.compile(pattern)print 'Text :', textprint 'Pattern :', patternprint 'Matches :', regex.findall(text)

结果
Text : This is some text – with punctuation.
Pattern : (?i)\bT\w+
Matches : [‘This’, ‘text’]

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