Python正则表达式例子讲解

因为字符串处理无所不在，正则毫无疑问是最简洁和高效的处理方法。今天我们要来一起梳理的知识点就是Python正则表达式。本文将用十个Python正则表达式的例子，帮助初学者入门Python正则表达式，下面一起来看看吧~

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1、查找第一个匹配串

s = 'i love python very much'

pat = 'python'

r = re.search(pat,s)

print(r.span()) #(7,13)

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2、查找所有1

s = '山东省潍坊市青州第1中学高三1班'

pat = '1'

r = re.finditer(pat,s)

for i in r:

print(i)

# <re.Match object; span=(9, 10), match='1'>

# <re.Match object; span=(14, 15), match='1'>

3、\d匹配数字[0-9]

s = '一共20行代码运行时间13.59s'

pat = r'\d+' # +表示匹配数字(\d表示数字的通用字符)1次或多次

r = re.findall(pat,s)

print(r)

# ['20', '13', '59']

4、表示前一个字符匹配0或1次

s = '一共20行代码运行时间13.59s'

pat = r'\d+\.?\d+' # ?表示匹配小数点(\.)0次或1次

r = re.findall(pat,s)

print(r)

# ['20', '13.59']

5、^匹配字符串的开头

s = 'This module provides regular expression matching operations similar to those found in Perl'

pat = r'^[emrt]' # 查找以

r = re.findall(pat,s)

print(r)

# [],因为字符串的开头是字符`T`，不在emrt匹配范围内，所以返回为空

6、re.I 忽略大小写

s = 'This module provides regular expression matching operations similar to those found in Perl'

pat = r'^[emrt]' # 查找以

r = re.compile(pat,re.I).search(s)

print(r)

# <re.Match object; span=(0, 1), match='T'> 表明字符串的开头在匹配列表中

7、使用正则提取单词

s = 'This module provides regular expression matching operations similar to those found in Perl'

pat = r'\s[a-zA-Z]+'

r = re.findall(pat,s)

print(r) #[' module', ' provides', ' regular', ' expression', ' matching', ' operations', ' similar', ' to', ' those', ' found', ' in', ' Perl']

8、只捕获单词，去掉空格

s = 'This module provides regular expression matching operations similar to those found in Perl'

pat = r'\s([a-zA-Z]+)'

r = re.findall(pat,s)

print(r) #['module', 'provides', 'regular', 'expression', 'matching', 'operations', 'similar', 'to', 'those', 'found', 'in', 'Perl']

9、补充上第一个单词

s = 'This module provides regular expression matching operations similar to those found in Perl'

pat = r'\s?([a-zA-Z]+)'

r = re.findall(pat,s)

print(r) #['This', 'module', 'provides', 'regular', 'expression', 'matching', 'operations', 'similar', 'to', 'those', 'found', 'in', 'Perl']

10、使用split函数直接分割单词

使用以上方法分割单词，不是简洁的，仅仅为了演示。分割单词最简单还是使用 split 函数。

s = 'This module provides regular expression matching operations similar to those found in Perl'

pat = r'\s+'

r = re.split(pat,s)

print(r) # ['This', 'module', 'provides', 'regular', 'expression', 'matching', 'operations', 'similar', 'to', 'those', 'found', 'in', 'Perl']