* Lists

*** Outline

***** Lists

***** Tuples

***** Arsenal Required

*** Script

	Welcome friends. 

	In this tutorial we shall look at some special Data structures 

	supported by Python namely Lists and Tuples. We have already been

	introduced to lists in some of the previous tutorials, here we

	shall look at them in little more detail.

	The list type is a container that holds a number of other 

	First lets start the interpreter by typing ipython in terminal.

	We create our first list by typing 

	num = [1, 2, 3, 4]

	Items enclosed in square brackets separated by comma 

	constitutes a list.

	One neat feature of Python list is that we can store data of any 

	type in them. We can have a list something like:

	var = [1, 1.2, 'string']

	print var

	Similar to strings, we can concatenate two lists using '+' 

	operator

	To add single object at the end of a list the 'append' 

	function is used

	num.append(-5)

	append takes only one argument. And append behaves different 

	num.append([9, 10, 11])

	num = [1, 4, -6]

	num.extend([2, 8, 0])

	num.reverse()

	Now after using reverse function, lets check the value of 'num'

	To remove a particular element from the list Python provides

	the remove() function

	num.remove(8)

	if the given argument is present more than once in the list, 

	then the first occurrence of that element is removed from list.

	The Slicing and Striding concepts which we covered for Arrays work

	with lists as well. Lets revisit the concept by looking at some examples

	a = [1, 2, 3, 4, 5]

	One important feature of list indexing is the negative index. In

	Lists -1 indicates last element of the list

	similarly -2 will be second last and so forth. Now these 

	negative indexes can also be used with slicing. If we try

	we get list which excludes first and last element of a.

	and if we do not specify the start or the end index value the default 

	values are taken. The default values being the first element and the 

	last element.

	We can perform striding as well, by specifying the step size

	This gives second, fourth and so on items of a till we reach 

	last item of list.

	With step sizes, if we specify negative values we get some 

	interesting results. Lets try

	Let's look at the contents of num

	To check if the number 4 is present in the list we type

	True

	Python provides support for special immutable lists known as

	'tuple'	To create a tuple instead we use normal brackets '('

	unlike '[' for lists.

	t = (1, 2, 3, 4, 5, 6, 7, 8)

	but operation like

	t[4] = 7 are not allowed

	These features of tuples have their advantages. To see where 

	are they used we first create two variables

	a, b = 1, 6

	print a, b

	As you can see multiple variable assignments are possible using

	tuples.

	Now lets swap values their values. Normal approach would be 

	to create a temporary to hold the value but because of tuples

	we can do something cool like

	b, a = a, b

	print a, b

	and values are swapped. And this swapping works for all types

	of variables. This is possible because of something magical 

	that Python does called	as tuple packing and unpacking.

	With this we come to the end of this tutorial on Lists and 

*** Notes