Summary of usage instances of the Python Express expression

Regular expression is a very useful function in Python program design, this article makes a summary of common regular expressions, for everyone's reference. Specific as follows:

One, string substitution

1. Replace all matching substrings

Replace all substrings in the subject with regex matching the regular expression with newstring

result, Number = RE.SUBN (regex, newstring, subject)

2. Replace all matching substrings (using regular Expression objects)

Reobj = Re.compile (regex) result, Number = REOBJ.SUBN (newstring, subject)

Second, string splitting

1. String splitting

result = Re.split (regex, subject)

2. String splitting (use regular Expression object)

Reobj = Re.compile (regex) result = Reobj.split (subject)

Third, matching

The following are some of the matching usages of Python regular expressions:

1. Test whether the regular expression matches all or part of the string

Regex=ur "..." #正则表达式if re.search (Regex, subject):  do_something () Else:  do_anotherthing ()

2. Test whether the regular expression matches the entire string

Regex=ur "... \z" #正则表达式末尾以 \z End If Re.match (Regex, subject):  do_something () Else:  do_anotherthing ()

3. Create a matching object and then get the matching details from that object

Regex=ur "..." #正则表达式match = Re.search (regex, subject) if match:  # match Start:match.start ()  # match End (Exclusiv E): Match.end ()  # matched Text:match.group ()  do_something () Else:  do_anotherthing ()

4. Get the substring that matches the regular expression

(Get the part of a string matched by the regex) Regex=ur "..." #正则表达式match = Re.search (regex, subject) If match:  result = Match.group () Else:  result = ""

5. Get the substring that the capturing group matches

(Get the part of a string matched by a capturing group) Regex=ur "..." #正则表达式match = Re.search (regex, subject) if match:  result = Match.group (1) Else:  result = ""

6. Get the substring matched by the named group

(Get the part of a string matched by a named group) Regex=ur "..." #正则表达式match = Re.search (regex, subject) If match:  ResU lt = Match.group ("groupname") Else:  result = ""

7. Put all matching substrings in the string into the array

(Get an array of all regex matches in a string) result = Re.findall (regex, subject)

8. Traverse all matching substrings

(Iterate-all matches-a string) for match in Re.finditer (R "< (. *?) \s*.*?/\1> ", subject)  # match Start:match.start ()  # match End (exclusive): Match.end ()  # matched Text:ma Tch.group ()

9. Create a regular expression object from a regular expression string

(Create an object to use the same regex for many operations) Reobj = Re.compile (regex)

10. Usage 1 of the regular Expression object version

(Use Regex object for If/else branch whether (part of) A string can be matched) Reobj = Re.compile (regex) if Reobj.search (su bject):  do_something () Else:  do_anotherthing ()

11. Usage 2 of the regular Expression object version

(Use Regex object for If/else branch whether a string can be matched entirely) Reobj = Re.compile (r "\z") #正则表达式末尾以 \z End If R Eobj.match (subject):  do_something () Else:  do_anotherthing ()

12. Create a regular Expression object and then get the matching details from that object

(Create an object with details on how to the Regex object matches (part of) a string) Reobj = Re.compile (regex) match = Reob J.search (subject) If match:  # match Start:match.start ()  # match End (exclusive): Match.end ()  # matched text: Match.group ()  do_something () Else:  do_anotherthing ()

13. Get the matching substring with the regular expression object

(Use Regex object to get the part of a string matched by the regex) Reobj = Re.compile (regex) match = Reobj.search (subject) I F match:  result = Match.group () Else:  result = ""

14. Get the substring matching the capturing group with the regular expression object

(Use Regex, object to get, part of a, string matched by a capturing group) Reobj = Re.compile (regex) match = Reobj.search (s Ubject) If match:  result = Match.group (1) Else:  result = ""

15. Use regular Expression object to get the substring matching the well-known group

(Use Regex object to get the part of a string matched by a named group) Reobj = Re.compile (regex) match = Reobj.search (subje CT) If match:  result = Match.group ("groupname") Else:  result = ""

16. Get all matched substrings with the regular expression object and put them in the array

(Use Regex object to get an array of all regex matches in a string) Reobj = Re.compile (regex) result = Reobj.findall (subject )

17. Traverse all matching substrings through the regular expression object

(Use Regex-object to iterate-over-all matches-a string) Reobj = Re.compile (regex) for match in Reobj.finditer (subject): 
  # match Start:match.start ()  # match End (exclusive): Match.end ()  # matched Text:match.group ()

Interested readers can start debugging This example code, I believe there will be a new harvest.

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