re(續):

　　re默認是貪婪模式。

　　貪婪模式:在滿足匹配時,匹配盡可能長的字符串。

import re
s = ‘askldlaksdabccccccccasdabcccalsdacbcccacbcccabccc‘

res = re.findall(‘abc+‘,s)
print(res)

res = re.findall(‘abc+?‘,s)    #在規則後面加?來取消貪婪模式。
print(res)

執行結果:
D:\Python\Python36-32\python.exe E:/Python/DAY-15/3213.py
[‘abcccccccc‘, ‘abccc‘, ‘abccc
 
‘]
[‘abc‘, ‘abc‘, ‘abc‘]

Process finished with exit code 0

re的模塊的常用方式:

re.split(): 類似字符串的split命令但是比 字符串的split 更強大。

import re
s = ‘askldlaksdab8ccccc.cccas8dabc8cc.alsdacbcccac.cccab8ccc‘

res = re.split(‘\d‘,s)
print(res)
res = re.split(‘(\d+)‘,s)    #加()來保留分割符
print(res)


執行結果:
D:\Python\Python36
 
-32\python.exe E:/Python/DAY-15/3213.py
[‘askldlaksdab‘, ‘ccccc.cccas‘, ‘dabc‘, ‘cc.alsdacbcccac.cccab‘, ‘ccc‘]
[‘askldlaksdab‘, ‘8‘, ‘ccccc.cccas‘, ‘8‘, ‘dabc‘, ‘8‘, ‘cc.alsdacbcccac.cccab‘, ‘8‘, ‘ccc‘]

Process finished with exit code 0

re.sub():類似replace 替換操作。

import re
s = ‘askldlaksdab8ccccc.cccas8dabc8cc.alsdacbcccac.cccab8ccc
 
‘

res = re.sub(‘abc+‘,‘123‘,s)
print(res)


執行結果:
D:\Python\Python36-32\python.exe E:/Python/DAY-15/3213.py
askldlaksdab8ccccc.cccas8d1238cc.alsdacbcccac.cccab8ccc

Process finished with exit code 0

re.compile():編譯

import re
s = ‘askldlaksdab8ccccc.cccas8dabc8cc.alsdacbcccac.cccab8ccc‘

obj = re.compile(‘\d+‘)   #定義一個對象對應的編譯規則
res = obj.findall(s)    #調用處理
print(res)

執行結果:
D:\Python\Python36-32\python.exe E:/Python/DAY-15/3213.py
[‘8‘, ‘8‘, ‘8‘, ‘8‘]

Process finished with exit code 0

一個小爬蟲正則練習(爬校花網)

import requests,re,json
url = ‘http://www.xiaohuar.com/2014.html‘    #校花排行榜top120
def req():
    req_str = requests.get(url)
    # print(‘encoding‘,req_str.encoding)
    return req_str.text

def run():
    html = req()
    html = html.encode(‘Latin-1‘).decode(‘gbk‘)
    # print(html)
    obj = re.compile(‘<div class="top-title">(.*?)</div>.*?<div class="title">.*?target="_blank">(.*?)</a></span></div>‘,re.S)   #匹配top排名序號和姓名學校
    res = obj.findall(html)
    return res

dic = {}
res = run()
for x in res:
    dic[x[0]]=x[1]
data = json.dumps(dic)       #序列化
with open(‘xiaohua.json‘,‘a‘,encoding=‘utf-8‘) as f:
    f.write(data)

with open(‘xiaohua.json‘, ‘r‘, encoding=‘utf-8‘) as f:
    data = json.load(f)   #反序列化
    print(data)

subprocess:

　　 subprocess模塊允許一個進程創建一個新的子進程，通過管道連接到子進程的stdin/stdout/stderr，獲取子進程的返回值等操作。

import subprocess

s = subprocess.Popen(‘dir‘,shell=True,stdout=subprocess.PIPE)
print(s.stdout.read().decode(‘gbk‘))

執行結果:
D:\Python\Python36-32\python.exe E:/Python/DAY-15/3213.py
 驅動器 E 中的卷沒有標簽。
 卷的序列號是 383D-453A

 E:\Python\DAY-15 的目錄

2017/06/27  19:52    <DIR>          .
2017/06/27  19:52    <DIR>          ..
2017/06/27  19:52               338 3213.py
2017/06/27  19:47               778 tmp.py
2017/06/27  19:25             9,146 xiaohua.json
               3 個文件         10,262 字節
               2 個目錄 117,877,260,288 可用字節


Process finished with exit code 0

Python基礎day-13[模塊：re,subprocess未完]