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python:twistedlxmlandre [2014/08/11 06:51] – [Build xml using Etree] adminpython:twistedlxmlandre [2022/10/29 16:15] (current) – external edit 127.0.0.1
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 </code> </code>
 ===== re Package(Regular Expression) ===== ===== re Package(Regular Expression) =====
 +To use re package, we need to import it:<code python>
 +import re
 +</code>
 ==== Regular Expression Language ==== ==== Regular Expression Language ====
 A regular expression (abbreviated regex or regexp) is a sequence of characters that forms a search pattern\\ A regular expression (abbreviated regex or regexp) is a sequence of characters that forms a search pattern\\
-refer: http://msdn.microsoft.com/en-us/library/az24scfc(v=vs.110).aspx+refer:  
 +  * http://msdn.microsoft.com/en-us/library/az24scfc(v=vs.110).aspx 
 +  * python: https://docs.python.org/2/library/re.html#regular-expression-syntax
  
 **Match Character** **Match Character**
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 </code> </code>
 === re.findall === === re.findall ===
-  * re.findall: The findall() is probably the single most powerful function in the re module<code python>+findall: The findall() is probably the single most powerful function in the re module 
 +  - Example 1: <code python>
 str = 'purple alice@google.com, blah monkey bob@abc.com blah dishwasher' str = 'purple alice@google.com, blah monkey bob@abc.com blah dishwasher'
  
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     # do something with each found email string     # do something with each found email string
     print email     print email
-</code>    <code python>+</code>Understand pattern syntax above: 
 +  * [\w\.-]+ => Begin with one or multiple(sign: +) in group(sign: []): word(sign: \w) or character **.**(sign: \.) or character **-** 
 +  * @[\w\.-]+ => next of it is character @ and one or multiple characters in group: [word, **.** , **-**] 
 +  - Example 2: <code python>
 # Open file # Open file
 f = open('test.txt', 'r') f = open('test.txt', 'r')
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 text2 = re.sub("cool", "good", text) text2 = re.sub("cool", "good", text)
 print text2 print text2
 +</code>output<code>
 +Python for beginner is a very good website
 </code> </code>
       * Here is another example (taken from Googles Python class ) which searches for all the email addresses, and changes them to keep the user (1) but have yo-yo-dyne.com as the host.<code python>       * Here is another example (taken from Googles Python class ) which searches for all the email addresses, and changes them to keep the user (1) but have yo-yo-dyne.com as the host.<code python>
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 ## 1 is group(1), 2 group(2) in the replacement ## 1 is group(1), 2 group(2) in the replacement
  
-print re.sub(r'([w.-]+)@([w.-]+)', r'1@yo-yo-dyne.com', str) +print re.sub(r'([\w.-]+)@([\w.-]+)', r'1@yo-yo-dyne.com', str)
 ## purple alice@yo-yo-dyne.com, blah monkey bob@yo-yo-dyne.com blah dishwasher ## purple alice@yo-yo-dyne.com, blah monkey bob@yo-yo-dyne.com blah dishwasher
 +</code>output:<code>
 +purple alice@yo-yo-dyne.com, blah monkey bob@yo-yo-dyne.com blah dishwasher
 </code> </code>
   * re.compile: With the re.compile() function we can compile pattern into pattern objects, which have methods for various operations such as searching for pattern matches or performing string substitutions.    * re.compile: With the re.compile() function we can compile pattern into pattern objects, which have methods for various operations such as searching for pattern matches or performing string substitutions. 
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