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−.. Objectives
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−.. ----------
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−
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−.. A - Students and teachers from Science and engineering backgrounds
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−   B - Will learn what are tuples and why they are needed
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−       Will learn the various methods of accessing elements in tuples
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−   C - 
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−   D - 
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−
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−.. #. what are tuples
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−.. #. comparison with lists
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−.. #. why are they needed
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−
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−
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−.. Prerequisites
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−.. -------------
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−
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−..   1. Getting started with lists
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−     
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−.. Author              : Nishanth Amuluru
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−   Internal Reviewer   : 
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−   External Reviewer   :
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−   Checklist OK?       : <put date stamp here, if OK> [2010-10-05]
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−
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−Script
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−------
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−
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−Hello friends and welcome to the tutorial on Tuples
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−
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−{{{ Show the slide containing title }}}
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−
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−{{{ Show the slide containing the outline slide }}}
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−
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−In this tutorial, we shall learn
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−
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− * what are tuples
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− * their similarities and dissimilarities with lists
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− * why are they needed
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−
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−Let`s get started by defining a tuple. A tuple is defined by enclosing
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−parantheses around a sequence of items seperated by commas. It is similar to
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−defining a list except that parantheses are used instead of square brackets.
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−::
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−
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−    t = (1, 2.5, "hello", -4, "world", 1.24, 5)
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−    t
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−
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−defines a tuple. The items in the tuple are indexed using numbers and can be 
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−accessed by using their position.
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−::
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−
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−    t[3]
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−
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−prints -4 which is the fourth item of the tuple.
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−
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−::
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−
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−    t[1:5:2]
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−
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−prints the corresponding slice
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−
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−This is the behaviour similar as to lists. But the difference can be seen when
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−we try to change an element in the tuple.
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−::
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−
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−    t[2] = "Hello"
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−
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−We can see that, it raises an error saying tuple does not support item
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−assignment. It only implies that tuples are immutable or in simple words,
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−tuples cannot be changed.
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−
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−But what is the use of tuples!!!
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−
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−We shall understand that soon. But let us look at a simple problem of swapping
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−values.
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−
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−{{{ Pause here and try out the following exercises }}}
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−
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−%% 1 %% a = 5 and b = 7. swap the values of a and b
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−
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−{{{ continue from paused state }}}
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−::
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−
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−    a = 5
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−    b = 7
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−
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−    a
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−    b
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−
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−We define the two values
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−::
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−
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−    temp = a
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−    a = b
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−    b = temp
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−
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−    a
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−    b
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−
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−This is the traditional approach
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−
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−Now let us do it the python way
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−::
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−
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−    a
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−    b
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−
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−    a, b = b, a
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−
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−    a
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−    b
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−
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−We see that the values are swapped.
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−This idiom works for different datatypes also.
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−::
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−
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−    a = 2.5
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−    b = "hello"
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−
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−    a
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−    b
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−
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−Moreover this type of behaviour is straight forward and what you would expect
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−should happen naturally.
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−
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−This is possible because of the immutability of tuples. This process is called
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−tuple packing and unpacking.
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−
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−Let us first see what is tuple packing. Type
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−::
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−
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−    5,
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−
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−What we see is a tuple with one element.
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−::
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−
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−    5, "hello", 2.5
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−
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−Now it is a tuple with two elements.
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−
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−So when we are actually typing two or more elements seperated by commas, those
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−elements are packed and a tuple is made from them.
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−
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−When you type
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−::
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−
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−    a, b = b, a
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−
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−First the values of b and a are packed into a tuple on the right side and then
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−unpacked into the variables a and b.
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−
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−Immutability of tuples ensures that the values are not changed during the
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−packing and unpacking.
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−
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−{{{ Show summary slide }}}
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−
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−This brings us to the end of the tutorial.
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−we have learnt
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−
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− * How to define tuples
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− * The similarities of tuples with lists, like indexing and iterability
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− * The immutability of tuples
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− * The value swapping idiom in Python
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− * packing and unpacking of tuples
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−
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−{{{ Show the "sponsored by FOSSEE" slide }}}
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−
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−#[Nishanth]: Will add this line after all of us fix on one.
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−This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India
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−
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−Hope you have enjoyed and found it useful.
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−Thankyou
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−