In Python, you can extend a list and you can append to it as well.

What's the difference? If you append a list to another list, you add the new list as a single extra list to the original, thus makingthe original list just one longer with an item that is itself a list. But if you extend a list with another list, you add each element of the new list onto the original. Here's an example to show you what I mean:

>>> first = [10,20,30]
>>> second = [40,50,60]
>>> first.append([70,80,90])
>>> second.extend([100,110,120])
>>> first
[10, 20, 30, [70, 80, 90]]
>>> second
[40, 50, 60, 100, 110, 120]
>>>


Illustration - delegates come on our Python courses from near and far. For delegates who are new to the UK, we try to provide "a taste of England" too - taking lunch at a variety of interesting places. Pictured - course delegates at Lacock, about 4 miles from our training centre
(written 2006-10-20, updated 2010-06-20)

 Y104 - Python - Lists and Tuples
  [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)
  [955] Python collections - mutable and imutable - (2006-11-29)
  [657] The ternary operator in Python - (2006-03-25)
  [383] Overloading of operators on standard objects in Python - (2005-07-19)

Y111 - Python - More on Collections and Sequences
  [3439] Python for loops - applying a temporary second name to the same object - (2011-09-14)
  [3150] Python dictionaries - mutable and immutable keys and values - (2011-01-29)
  [2920] Sorting - naturally, or into a different order - (2010-08-14)
  [2894] Sorting people by their names - (2010-07-29)
  [2718] Python - access to variables in the outer scope - (2010-04-12)
  [1873] List Comprehensions in Python - (2008-11-06)
  [1869] Anonymous functions (lambdas) and map in Python - (2008-11-04)
  [1310] Callbacks - a more complex code sandwich - (2007-08-19)
  [1304] Last elements in a Perl or Python list - (2007-08-16)
  [633] Copying a reference, or cloning - (2006-03-05)
  [386] What is a callback? - (2005-07-22)
  [61] Python is a fabulous language - (2004-09-24)

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