Python Regex Object and Methods

By Xah Lee. Date: . Last updated: .

Compile Regex Object

re.compile(pattern) → Compiles regex pattern into a object. A regex object can be used by regex object methods. For example, RegexObj.search(…).

re.compile(pattern,flags) → use flags. [see Python Regex Flags]

The use of regex object is similar to re module functions. For example, the following 2 have the same result.

Creating a regex object is useful when you need to use the same pattern on many strings. This is more efficient because python doesn't have to compile the regex pattern internally each time.

The following detail regex object methods. Most of them have the same syntax as regex functions, but some are more flexible with optional parameters. [see Python Regex Functions]

Regex Object Methods

search

RegexObj.search(string)re.compile(pattern).search(string) is equivalent to re.search(pattern, string). [see Python Regex Functions]

RegexObj.search(string, startpos) → match on substring starting at startpos.

RegexObj.search(string, startpos, endpos) → end at endpos.

The following have the same result:

match

RegexObj.match(string) → same result as re.match(pattern, string). [see Python Regex Functions]

RegexObj.match(string, startpos) → match on substring starting at startpos.

RegexObj.match(string, startpos, endpos) → end at endpos

split

RegexObj.split(string, ) → same result as re.split(pattern, string, ). [see Python Regex Functions]

findall

RegexObj.findall(string) → same result as re.findall(pattern, string)

RegexObj.findall(string, startpos) → match on substring starting at startpos.

RegexObj.findall(string, startpos, endpos) → end at endpos.

finditer

RegexObj.finditer(string) → same result as re.finditer(pattern, string)

RegexObj.finditer(string, startpos) → match on substring starting at startpos.

RegexObj.finditer(string, startpos, endpos) → end at endpos.

sub

RegexObj.sub( repl, string, ) → same result as re.sub(pattern, string, ).

subn

RegexObj.subn( repl, string, ) → same result as re.subn(pattern, string, )

Regex Attributes

The following are constants assigned by the module when a pattern object is compiled.

.flags

RegexObj.flags → The flags argument used when the regex object was compiled, or 0 if no flags were provided.

import re
patObj = re.compile(ur'\w', re.M|re.U)
print patObj.flags  # prints 40

.groupindex

RegexObj.groupindex → return a dictionary. The keys are the named capture groups, the values are their order in the pattern. For example, here's a pattern of named group (?P<id>). The dictionary is empty if no symbolic groups were used in the pattern.

# -*- coding: utf-8 -*-
# python 2

# example of regex .groupindex

import re

# a typical image tag
# <img src="cat.jpg" alt="cat" width="123" height="456">

# a pattern to capture image tag, with named group
xx = re.compile(r'src="(?P<filename>[^"]+)" alt="(?P<alttext>[^"]+)" width="(?P<width>\d+)" height="(?P<height>\d+)"')

print xx.groupindex #  {'height': 4, 'width': 3, 'alttext': 2, 'filename': 1}

.pattern

RegexObj.pattern → The pattern string from which the regex object was compiled.

If you have a question, put $5 at patreon and message me.

Python

  1. Python 3 Basics
  2. Python 2 Basics
  3. Python 2 and 3 Difference
  4. Print Version
  5. Builtin Help
  6. Quote String
  7. String Methods
  8. Format String
  9. Operators
  10. Complex Numbers
  11. True, False
  12. if then else
  13. Loop
  14. List Basics
  15. Loop Thru List
  16. Map f to List
  17. Copy Nested List
  18. List Comprehension
  19. List Methods
  20. Sort
  21. Dictionary
  22. Loop Thru Dict
  23. Dict Methods
  24. Tuple
  25. Sets
  26. Function
  27. Closure
  28. 2 Closure
  29. Decorator
  30. Class
  31. Object, ID, Type
  32. List Modules
  33. Write a Module
  34. Unicode 🐍

Regex

  1. Regex Basics
  2. Regex Reference

Text Processing

  1. Read/Write File
  2. Traverse Directory
  3. File Path
  4. Process Unicode
  5. Convert File Encoding
  6. Find Replace in dir
  7. Find Replace by Regex
  8. Count Word Frequency

Web

  1. Send Email
  2. GET Web Page
  3. Web Crawler
  4. HTTP POST

Misc

  1. JSON
  2. Find Script Path
  3. Get Env Var
  4. System Call
  5. Decompress Gzip
  6. Append String in Loop
  7. Timing f timeit
  8. Keyword Arg Default Value Unstable
  9. Check Page Load Size
  10. Thumbnail Generation