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Python Programming 101
Revision of Regular Expressions from Tue, 2011-05-31 05:46
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In computing, a regular expression, also referred to as regex or regexp, provides a concise and flexible means for matching strings of text, such as particular characters, words, or patterns of characters.
The following examples illustrate a few specifications that could be expressed in a regular expression:
- The sequence of characters "car" appearing consecutively in any context, such as in "car", "cartoon", or "bicarbonate"
- The sequence of characters "car" occurring in that order with other characters between them, such as in "Icelander" or "chandler"
- The word "car" when it appears as an isolated word
- The word "car" when preceded by the word "blue" or "red"
- The word "car" when not preceded by the word "motor"
- A dollar sign immediately followed by one or more digits, and then optionally a period and exactly two more digits (for example, "$100" or "$245.99").
Source: Wikipedia
Python regular expression syntax follows in the Perl lineage. The Python module re provides regular expression functionality. Regular Expressions are a sub-language embedded within the larger Python language.
Educational Resources
- Chapter 11 - Regular Expressions (Slides, Printable Slides, Download Video, Streaming Video)
Python.org
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Chap
Chap 11
http://www.pastie.org/2066794
Chapter 11 Exercises:
Chapter 11 Exercises: https://github.com/jwmnatl/jwmnatl.github.com/blob/master/python101/chap...
For Ex. 11.2, my average for mbox.txt was 39607.
I received smaller number of lines than those referenced in Ex. 11.1 :
e.g. -
Enter a regular expression: ^Author
mbox.txt had 339 lines that matched ^Author
Enter a regular expression: ^X-
mbox.txt had 2715 lines that matched ^X-
Enter a regular expression: java$
mbox.txt had 510 lines that matched java$
Exercises chapter 11:
Exercises chapter 11: http://www.pastie.org/2021643
The average I found for exercise 11.2 using mbox.txt was 38549.7949721
Chapter 11 stuff up at:
Chapter 11 stuff up at: https://github.com/thcipriani/thcipriani.github.com/blob/master/python10...