--- a/manipulating-lists.rst Wed Oct 13 11:11:40 2010 +0530
+++ /dev/null Thu Jan 01 00:00:00 1970 +0000
@@ -1,180 +0,0 @@
-Hello friends. Welcome to this spoken tutorial on Getting started with
-strings.
-
-{{{ Show the slide containing the title }}}
-
-{{{ Show the slide containing the outline }}}
-
-We have already learnt a lot about Lists in Python. In this tutorial,
-we will learn more about advanced features of Lists in Python. We will
-see in detail how to concatenate two lists, slicing and striding of
-lists, methods to sort and reverse the list.
-
-{{{ Shift to terminal and start ipython }}}
-
-To begin with let us start ipython, by typing::
-
- ipython
-
-on the terminal
-
-We already know what Lists are in Python, how to access individual
-elements in the list and some of the functions that can be run on the
-lists like max, min, sum len and so on. Now let us learn some of the
-basic operations that can be performed on Lists.
-
-We already know how to access individual elements in a List. But what
-if we have a scenario where we need to get a part of the entire list
-or what we call as a slice of the list? Python supports slicing on
-lists. Let us say I have the list::
-
- primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29]
-
-To obtain the all the primes between 10 and 20 from the above list of
-primes we say::
-
- primes[4:8]
-
-This gives us all the elements in the list starting from the element
-with the index 4 which is 11 in our list upto the element with index 8
-in the list but not including the eigth element. So we obtain a slice
-starting from 11 upto 19th. It is a very important to remember that
-when ever we specify a range of elements in Python the start index is
-included and end index is not included. So in the above case, 11 which
-was the element with the index 4 was included but 23 which was the
-element with index 8 was exluded.
-
-Generalizing, we can obtain a slice of the list "p" from the index
-"start" upto the index "end" but excluding "end" with the following
-syntax
-
-{{{ Show the slide containing p[start:stop] }}}
-
-By default the slice fetches all the elements between start and stop
-including start but not stop. So as to say we obtain all the elements
-between start and stop in steps of one. Python also provides us the
-functionality to specify the steps in which the slice must be
-obtained. Say we have::
-
- num = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]
-
-If we want to obtain all the odd numbers less than 10 from the list
-"num" we have to start from element with index 1 upto the index 10 in
-steps of 2::
-
- num[1:10:2]
-
-So if we don't specify the step it is by default 1. Similary there are
-default values for start and stop indices as well. If we don't specify
-the start index it is implicitly taken as the first element of the
-list::
-
- num[:10]
-
-This gives us all the elements from the beginning upto the 10th
-element but not including the 10th element in the list "num". Similary
-if the stop index is not specified it is implicitly assumed to be the
-end of the list, including the last element of the list::
-
- num[10:]
-
-gives all the elements starting from the 10th element in the list
-"num" upto the final element including that last element. Now::
-
- num[::2]
-
-gives us all the even numbers in the list "num".
-
-The other basic operation that we can perform on list is concatenation
-of two or more lists. We can combine two lists by using the "plus"
-operator. Say we have
-
-{{{ Read as you type }}}::
-
- a = [1, 2, 3, 4]
- b = [4, 5, 6, 7]
- a + b
-
-When we concatenate lists using the "plus" operator we get a new
-list. We can store this list in a new variable::
-
- c = a + b
- c
-
-It is important to observe that the "plus" operator always returns a
-new list without touching anything in the existing lists which are the
-operands of the concatenation operation.
-
-We know that list is a collection of data. Whenever we have a
-collection we run into situations where we want to start the
-collection. Lists support sort method which sorts the list inplace::
-
- a = [5, 1, 6, 7, 7, 10]
- a.sort()
-
-Now the contents of the list "a" will be::
-
- a
- [1, 5, 6, 7, 7, 10]
-
-Since the sort method sorts the list inplace the original list we had
-is overwritten or replaced. We have no way to obtain the original list
-back. One way to avoid this is to keep a copy of the original list in
-another variable and run the sort method on the list. However Python
-also provides a built-in function called sorted which sorts the list
-which is passed as an argument to it and returns a new sorted list::
-
- a = [5, 1, 6, 7, 7, 10]
- sorted(a)
-
-We can store this sorted list another list variable::
-
- sa = sorted(a)
-
-Similarly to perform certain operations on the list we would like to
-reverse the list. Python provides reverse method which again reverses
-the list inplace::
-
- a = [1, 2, 3, 4, 5]
- a.reverse()
-
-reverses the list "a" and stores the reversed list inplace i.e. in "a"
-itself. Lets see the list "a"::
-
- a
- [5, 4, 3, 2, 1]
-
-But again the original list is lost. If we want to obtain the reverse
-of a list keeping the original list intact we can use the Python
-built-in function reversed. reversed function returns a new list which
-is the reverse of the list which was passed as the argument to the
-reversed function::
-
- a = [1, 2, 3, 4, 5]
- reversed(a)
-
-We can also store this new reversed list in another list variable.
-
-{{{ Show summary slide }}}
-
-This brings us to the end of another session. In this tutorial session
-we learnt
-
- * How to define strings
- * Different types of defining a string
- * String concatenation and repeatition
- * Accessing individual elements of the string
- * Immutability of strings
-
-{{{ Show the "sponsored by FOSSEE" slide }}}
-
-This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India
-
-Hope you have enjoyed and found it useful.
-Thankyou
-
-.. Author : Madhu
- Internal Reviewer 1 : [potential reviewer: Nishanth]
- Internal Reviewer 2 : [potential reviewer: Amit]
- External Reviewer :
-