Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
 
Python and Tcl - public course schedule [here]
Private courses on your site - see [here]
Please ask about maintenance training for Perl, PHP, Lua, etc
 
Python collections - mutable and imutable

Should you use a list or a tuple ... or perhaps a dictionary to store a collection of objects in your Python program? To help you make the decision, think whether you need to be able to modify the collection after you've created it (mutable) or not (immutable), and whether you want it to be indexed in order, or not.
Those two answers should lead to your collection type:
 UnorderedOrdered
MutableDictionary
{ and }
List
[ and ]
Immutablen/aTuple
( and )

If you want an immutable unordered collection (the empty box in my table), use a dictionary. And when you're initially creating the collection, use ( ), [ ] or { } as shown in the table. Always use [ and ] to reference member elements after the initial creation - Python does it like that to render any code you write polymorphic ... i.e. to be common code that will work whatever the collection type.
(written 2006-11-29, updated 2006-12-01)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
Y104 - Python - Lists and Tuples
  [4722] Embedding more complex code into a named block - (2016-11-04)
  [4368] Shuffling a list - Ruby and Python - (2014-12-28)
  [4027] Collections in Python - list tuple dict and string. - (2013-03-04)
  [3763] Spike solutions and refactoring - a Python example - (2012-06-13)
  [3669] Stepping through a list (or an array) in reverse order - (2012-03-23)
  [3348] List slices in Python - 2 and 3 values forms, with an uplifting example - (2011-07-06)
  [3257] All possible combinations from a list (Python) or array (Ruby) - (2011-04-23)
  [3181] Beware - a=a+b and a+=b are different - Python - (2011-02-23)
  [3118] Arrays of arrays - or 2D arrays. How to program tables. - (2011-01-02)
  [2996] Copying - duplicating data, or just adding a name? Perl and Python compared - (2010-10-12)
  [2719] Traffic lights in Python - (2010-04-13)
  [2368] Python - fresh examples of all the fundamentals - (2009-08-20)
  [2284] Strings as collections in Python - (2009-07-12)
  [2280] Creating and iterating through Python lists - (2009-07-12)
  [1789] Looking for a value in a list - Python - (2008-09-08)
  [1641] Tektronix 4010 series / Python Tuples - (2008-05-13)
  [1220] for loop - how it works (Perl, PHP, Java, C, etc) - (2007-06-06)
  [899] Python - extend v append on a list - (2006-10-20)
  [657] The ternary operator in Python - (2006-03-25)
  [383] Overloading of operators on standard objects in Python - (2005-07-19)

Y107 - Python - Dictionaries
  [4668] Sorting a dict in Python - (2016-04-01)
  [4661] Unique word locator - Python dict example - (2016-03-06)
  [4469] Sorting in Python 3 - and how it differs from Python 2 sorting - (2015-04-20)
  [4409] Setting up and using a dict in Python - simple first example - (2015-01-30)
  [4029] Exception, Lambda, Generator, Slice, Dict - examples in one Python program - (2013-03-04)
  [3934] Multiple identical keys in a Python dict - yes, you can! - (2012-11-24)
  [3662] Finding all the unique lines in a file, using Python or Perl - (2012-03-20)
  [3555] Football league tables - under old and new point system. Python program. - (2011-12-18)
  [3554] Learning more about our web site - and learning how to learn about yours - (2011-12-17)
  [3488] Python sets and frozensets - what are they? - (2011-10-20)
  [3464] Passing optional and named parameters to python methods - (2011-10-04)
  [2994] Python - some common questions answered in code examples - (2010-10-10)
  [2986] Python dictionaries - reaching to new uses - (2010-10-05)
  [2915] Looking up a value by key - associative arrays / Hashes / Dictionaries - (2010-08-11)
  [1145] Using a list of keys and a list of values to make a dictionary in Python - zip - (2007-04-13)
  [1144] Python dictionary for quick look ups - (2007-04-12)
  [103] Can't resist writing about Python - (2004-10-29)


Back to
Splitting Pythons in Bradford
Previous and next
or
Horse's mouth home
Forward to
Python security - trouble with input
Some other Articles
It's the 1st, not the 1nd 1rd or 1th.
Plain Ole nice pictures
Improving the historic town of Melksham
Python security - trouble with input
Python collections - mutable and imutable
Splitting Pythons in Bradford
Christmas in November
Coming from London to Melksham by train for a course
What happened at Geekmas
Python and the Magic Roundabout
4759 posts, page by page
Link to page ... 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96 at 50 posts per page


This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

Link to Ezine home page (for reading).
Link to Blogging home page (to add comments).

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2019: 404 The Spa • Melksham, Wiltshire • United Kingdom • SN12 6QL
PH: 01225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/mouth/955_Pyth ... table.html • PAGE BUILT: Sat May 27 16:49:10 2017 • BUILD SYSTEM: WomanWithCat