Python正則表達式小结

Posted 2020-09-27

学习一段python正則表達式了， 对match、search、findall、finditer等函数作一小结 

以下以一段网页为例，用python正則表達式作一个范例：

strHtml = '''<div> <a href="/user/student/" class="user-t"><img src="/uploads/avatar/2015/06/082e408c-14fc-11e5-a98d-00163e02100b_big.jpg"></a>
                      </div>
                       
                  </div>
                  <div class="navbar-search-btn visible-xs visible-sm">
                    <a href="/common/mobile/search/" class="sch"></a>
                  </div>
'''
print strHtml

#正則表達式  匹配如：< a href=”xxxxx” class=”xxxx”
remod = re.compile(r"<a href=\"([^\"]*)\" class=\"([^\"]*)\"")

search方法举例

search 会查找第一个找到匹配字符串并返回

item = remod.search(strHtml)
 
if item:
    print item.group()
else:
    print "no match [search]"     

# 输出：
# <a href="/user/student/" class="user-t"

match方法举例

match 会从字符串开头匹配查找第一个找到匹配字符串并返回

item = remod.match(strHtml, re.M|re.S)
   
if item:
    print item.group()
else:
print "no match [match]"no match [match]
 
# 输出
# no match [match]

findall方法举例

Findall查找全部找到匹配字符串并返回一个列表，假设有匹配的组（group）,那么它是这个列表下的一个元组

items = remod.findall(strHtml)   
if items:
    print items
    for it in items:
        print it
else:
    print "no match [findall]"

# 输出
# [('/user/student/', 'user-t'), ('/common/mobile/search/', 'sch')]
# ('/user/student/', 'user-t')
# ('/common/mobile/search/', 'sch')

finditer方法举例

finditer查找全部找到匹配字符串并返回一个group，能够通过下标引用， 以下从1開始

tems = remod.finditer(strHtml 
if items:
    for it in items:
        print "it.group():",it.group()
        print "it.group(0):",it.group(0)
        print "it.group(1):",it.group(1)
        print "it.group(2):",it.group(2)+"\n"
else:
print "no match [findall]"

# 输出
# it.group(): <a href="/user/student/" class="user-t"
# it.group(0): <a href="/user/student/" class="user-t"
# it.group(1): /user/student/
# it.group(2): user-t

# it.group(): <a href="/common/mobile/search/" class="sch"
# it.group(0): <a href="/common/mobile/search/" class="sch"
# it.group(1): /common/mobile/search/
# it.group(2): sch