這篇文章主要為大家展示了“python中re正則匹配網(wǎng)頁中圖片url地址的示例分析”,內容簡而易懂,條理清晰,希望能夠幫助大家解決疑惑,下面讓小編帶領大家一起研究并學習一下“python中re正則匹配網(wǎng)頁中圖片url地址的示例分析”這篇文章吧。
要抓取的圖片地址如圖所示:
首先,使用這個pattern
reg = re.compile('.*g_img={url: "(http.*?jpg)"')
無論怎么匹配都匹配不到,后來把網(wǎng)頁源碼抓下來放在notepad++中查看,并用notepad++的正則匹配查找,很輕易就匹配到了,如圖:
后來我寫了個測試代碼,把圖片地址在的那一行保存在一個字符串中,很快就匹配到了,如下面代碼所示,data是匹配不到的,然而line是可以匹配到的。
# -*-coding:utf-8-*- import os import re f = open('bing.html','r') line = r'''Bnp.Internal.Close(0,0,60056); } });;g_img={url: "https://az12410.vo.msecnd.net/homepage/app/2016hw/BingHalloween_BkgImg.jpg",id:'bgDiv',d:'200',cN''' data = f.read().decode('utf-8','ignore').encode('gbk','ignore') print " " reg = re.compile('.*g_img={url: "(http.*?jpg)"') if re.match(reg, data): m1 = reg.findall(data) print m1[0] else: print("data Not match .") print 20*'-' #print line if re.match(reg, line): m2 = reg.findall(line) print m2[0] else: print("line Not match .")
由此可見line和data是有區(qū)別的,什么區(qū)別呢?那就是data是多行的,包含換行符,而line是單行的,沒有換行符。我有在字符串line中加了換行符,結果line沒有匹配到。
到這了原因就清楚了。原因就在這句話
re.compile('.*g_img={url: "(http.*?jpg)"')。
后來翻閱python文檔,發(fā)現(xiàn)re.compile()這個函數(shù)的第二個可選參數(shù)flags。這個參數(shù)是re中定義的常量,有如下常量
re.DEBUG Display debug information about compiled expression. re.I re.IGNORECASE Perform case-insensitive matching; expressions like [A-Z] will match lowercase letters, too. This is not affected by the current locale.
re.L re.LOCALE Make \w, \W, \b, \B, \s and \S dependent on the current locale.
re.M re.MULTILINE When specified, the pattern character '^' matches at the beginning of the string and at the beginning of each line (immediately following each newline); and the pattern character '$' matches at the end of the string and at the end of each line (immediately preceding each newline). By default, '^' matches only at the beginning of the string, and '$' only at the end of the string and immediately before the newline (if any) at the end of the string.
re.S re.DOTALL Make the '.' special character match any character at all, including a newline; without this flag, '.' will match anything except a newline.re.U re.UNICODE Make \w, \W, \b, \B, \d, \D, \s and \S dependent on the Unicode character properties database.New in version 2.0.
re.X re.VERBOSE This flag allows you to write regular expressions that look nicer and are more readable by allowing you to visually separate logical sections of the pattern and add comments. Whitespace within the pattern is ignored, except when in a character class or when preceded by an unescaped backslash. When a line contains a # that is not in a character class and is not preceded by an unescaped backslash, all characters from the leftmost such # through the end of the line are ignored.
這里我們需要的就是re.S 讓'.'匹配所有字符,包括換行符。修改正則表達式為
reg = re.compile('.*g_img={url: "(http.*?jpg)"', re.S)
即可完美解決問題。
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