Regular Expressions in Python

I took advantage of the lack of a whiteboard yesterday to write notes on the screen - in an edit window - while I was teaching a class about regular expressions, and how they're used in Python. Which has resulted in a rather nice example that's now online [here].

Regular expressions can frighten newcomers. At time they appear to the uninitiated to be impenetrable strings of characters, but take a careful look, break them down into literals, groups, counts and assertions, and they become much more straightforward. I've put examples a summary of what each of the types is, together with some examples, in comments at the top of the training code.

My Python Regular Expression Example matches email addresses, splits an HTML stream into tags and content, and recognizes both the sort and long form of USA postcodes. As I was giving a Python Course in Dublin, I didn't use my more regular British postcode example as my delegates were unlikely to be familiar with the details of how those are formatted.

(written 2010-04-14, updated 2010-05-16)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles

Y115 - Additional Python Facilities
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  [3469] Teaching dilemma - old tricks and techniques, or recent enhancements? - (2011-10-08)
  [3442] A demonstration of how many Python facilities work together - (2011-09-16)
  [3089] Python regular expressions - repeating, splitting, lookahead and lookbehind - (2010-12-17)
  [2790] Joining a MySQL table from within a Python program - (2010-06-02)
  [2786] Factory methods and SqLite in use in a Python teaching example - (2010-05-29)
  [2765] Running operating system commands from your Python program - (2010-05-14)
  [2764] Python decorators - your own, staticmethod and classmethod - (2010-05-14)
  [2746] Model - View - Controller demo, Sqlite - Python 3 - Qt4 - (2010-04-29)
  [2745] Connecting Python to sqlite and MySQL databases - (2010-04-28)
  [2655] Python - what is going on around me? - (2010-02-28)
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  [2435] Serialization - storing and reloading objects - (2009-10-04)
  [2407] Testing code in Python - doctest, unittest and others - (2009-09-16)
  [1876] Python Regular Expressions - (2008-11-08)
  [1337] A series of tyre damages - (2007-09-08)
  [1336] Ignore case in Regular Expression - (2007-09-08)
  [1305] Regular expressions made easy - building from components - (2007-08-16)
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  [1136] Buffering output - why it is done and issues raised in Tcl, Perl, Python and PHP - (2007-04-06)
  [1043] Sending an email from Python - (2007-01-18)
  [901] Python - listing out the contents of all variables - (2006-10-21)
  [753] Python 3000 - the next generation - (2006-06-09)
  [672] Keeping your regular expressions simple - (2006-04-05)
  [663] Python to MySQL - (2006-03-31)
  [463] Splitting the difference - (2005-10-13)
  [239] What and why for the epoch - (2005-03-08)
  [208] Examples - Gadfly, NI Number, and Tcl to C interface - (2005-02-10)
  [183] The elegance of Python - (2005-01-19)

Y108 - Python - String Handling
  [4027] Collections in Python - list tuple dict and string. - (2013-03-04)
  [3886] Formatting output - why we need to, and first Python example - (2012-10-09)
  [3796] Backquote, backtic, str and repr in Python - conversion object to string - (2012-07-05)
  [3468] Python string formatting - the move from % to str.format - (2011-10-08)
  [3349] Formatting output in Python through str.format - (2011-07-07)
  [3218] Matching a license plate or product code - Regular Expressions - (2011-03-28)
  [3090] Matching to a string - what if it matches in many possible ways? - (2010-12-17)
  [2814] Python - splitting and joining strings - (2010-06-16)
  [2780] Formatted Printing in Python - (2010-05-25)
  [2692] Flexible search and replace in Python - (2010-03-25)
  [2406] Pound Sign in Python Program - (2009-09-15)
  [2284] Strings as collections in Python - (2009-07-12)
  [1608] Underlining in Perl and Python - the x and * operator in use - (2008-04-12)
  [1517] Python - formatting objects - (2008-01-24)
  [1195] Regular Express Primer - (2007-05-20)
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  [970] String duplication - x in Perl, * in Python and Ruby - (2006-12-07)
  [954] Splitting Pythons in Bradford - (2006-11-29)
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  [560] The fencepost problem - (2006-01-10)
  [496] Python printf - (2005-11-15)
  [324] The backtick operator in Python and Perl - (2005-05-25)

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