Python正则表达式
2015-11-03
一、re.search()
使用正则表达式<
import re
import nltk
In[12]: wsj = sorted(set(nltk.corpus.treebank.word()))
In[13]: ws = [w for w in wsj if re.search('ed$', w)]
In[15]: ws[:10]
Out[15]:
[u'62%-owned',u'Absorbed',u'Advanced',u'Alfred', u'Allied', u'Annualized', u'Arbitrage-related',
u'Asked',u'Atlanta-based', u'Bermuda-based']
通配符“.”可以用来匹配任何单个字符。假设有一个8个字母组成的字谜，j是第三个字母，t是第六个字母。每个空白单元格用句点隔开。
In[16]: ws = [w for w in wsj if re.search('^..j..t..$', w)]
In[18]: ws
Out[18]: [u'adjusted', u'rejected']
匹配除元音字母之外的所有字母
[^aeiouAEIOU]
?: 如果要使用括号来指定连接的范围，又不想选择要输出字符串，必须添加“?:”。
In[20]: re.findall(r'^.*(?:ing|ly|ed|ies)$', 'processing')
Out[20]: ['processing']
演示如何使用符号：\，{}，() 和 |
In[20]: ws = [w for w in wsj if re.search('^[0-9]+\.[0-9]+$', w)]
In[21]: ws[:5]
Out[21]: [u'0.0085', u'0.05', u'0.1', u'0.16', u'0.2']
In[22]: ws = [w for w in wsj if re.search('^[A-Z]+\$$', w)]
In[23]: ws
Out[23]: [u'C$', u'US$']
In[24]: ws = [w for w in wsj if re.search('^[0-9]{4}$', w)]
In[26]: ws[:5]
Out[26]: [u'1614', u'1637', u'1787', u'1901', u'1903']
In[27]: ws = [w for w in wsj if re.search('(ed|ing)$', w)]
In[28]: ws[:5]
Out[28]: [u'62%-owned', u'Absorbed', u'According', u'Adopting', u'Advanced']
分词
In[13]: raw = """'When I'M a Duchess,' she said to herself, (not in a very hopeful tone
... though), 'I won't have any pepper in my kitchen AT ALL. Soup does very
... well without--Maybe it's always pepper that makes people
... hot-tempered,'..."""
In[16]: re.split(r' ', raw)
Out[16]:
["'When",
"I'M",
'a',
"Duchess,'",...]
In[17]: re.split('[ \t\n]', raw)
Out[17]:
["'When",
"I'M",
'a',
"Duchess,'",...]