A summary of usage instances of Python's regular expressions _python

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

One, string substitution

1. Replace all matching substrings

Replaces all substrings in the subject with the regular expression regex 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 split

1. String splitting

result = Re.split (regex, subject)

2. String splitting (using regular expression objects)

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

Third, match

Several matching usages of the Python regular expression are listed below:

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 through the object

Regex=ur "..." #正则表达式
match = Re.search (regex, subject)
if match:
  # match Start:match.start ()
  # Match End (exclusive): Match.end ()
  # matched Text:match.group ()
  do_something ()
else:
  do_ Anotherthing ()

4. Gets the substring that the regular expression matches

(Get the part 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. Gets 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. Gets the substring that the named group matches

(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: Result
  = Match.group ("groupname")
else: Result
  = ""

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

(Get an array of all regex matches in a string)

result = Re.findall (regex, subject)

8. Iterate through all matching substrings

(Iterate over all matches in a string)

For the match in Re.finditer (R) < (. *?) \s*.*?/\1> ", subject)
  # match Start:match.start ()
  # match End (exclusive): Match.end ()
  # matched Text:ma Tch.group ()

9. Creating 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. The regular Expression object version of Usage 1

(Use Regex object with If/else branch whether (part of) A string can is matched)

Reobj = Re.compile (regex)
if Reobj.search (subject):
  do_something ()
Else:
  do_anotherthing ()

11. The regular Expression object version of Usage 2

(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 Reobj.match (subject):
  do_something ()
else:
  do_ Anotherthing ()

12. Create a regular Expression object, and then get the matching details through the object

(Create an object and details about how the Regex object matches (part of) a string)

Reobj = Re.compile (regex)
match = Reobj.search (subject)
if match:
  # match Start:match.start ()
  # Match End (exclusive): Match.end ()
  # matched Text:match.group ()
  do_something ()
else:
  do_ Anotherthing ()

13. Get matching substring with 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)
if match: Result
  = Match.group ()
Else: Result
  = ""

14. Get the substring matched by the capturing group with the regular expression object

(Use Regex object to get the part of a string matched by a capturing group)

Reobj = Re.compile (regex)
match = Reobj.search (subject)
if match: Result
  = Match.group (1)
else:
  result = ""

15. Get the substring matched by the named group with the regular expression object

(Use Regex object to get the part of a string matched by a named group)

Reobj = Re.compile (regex)
match = Reobj.search (subject)
if match: Result
  = Match.group ("groupname")
else: Result
  = ""

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

(Use Regex object-get "an array of ' all" regex matches in a string)

Reobj = Re.compile (regex) Result
= Reobj.findall (subject)

17. Traversal of all matching substrings through regular expression objects

(Use Regex object to iterate the all matches in a string)

Reobj = Re.compile (regex) for
match in Reobj.finditer (subject):
  # Match Start:match.start ()
  # match End (exc lusive): Match.end ()
  # matched Text:match.group ()

Interested readers can start debugging this article example code, I believe there will be new gains.