1 Hello friends and welcome to the tutorial on Sets

     2 

     3 {{{ Show the slide containing title }}}

     4 

     5 {{{ Show the slide containing the outline slide }}}

     6 

     7 In this tutorial, we shall learn

     8 

     9  * sets

    10  * operations on sets

    11 

    12 Sets are data structures which contain unique elements. In other words,

    13 duplicates are not allowed in sets.

    14 

    15 Lets look at how to input sets.

    16 type

    17 ::

    18  

    19     a_list = [1, 2, 1, 4, 5, 6, 7]

    20     a = set(a_list)

    21     a

    22      

    23 We can see that duplicates are removed and the set contains only unique

    24 elements. 

    25 ::

    26 

    27     f10 = set([1, 2, 3, 5, 8])

    28     p10 = set([2, 3, 5, 7])

    29 

    30 f10 is the set of fibonacci numbers from 1 to 10.

    31 p10 is the set of prime numbers from 1 to 10.

    32 

    33 Sets can be iterated upon just like lists and tuples. 

    34 ::

    35 

    36     for i in f10:

    37         print i,

    38 

    39 prints the elements of f10.

    40 

    41 The length and containership check on sets is similar as in lists and tuples.

    42 ::

    43 

    44     len(f10)

    45 

    46 shows 5. And

    47 ::

    48 

    49     2 in f10

    50 

    51 prints False

    52 

    53 The order in which elements are organised in a set is not to be relied upon 

    54 since sets do not support indexing. Hence, slicing and striding are not valid

    55 on sets.

    56 

    57 Various operations that we do on sets are possible here also.

    58 The | character stands for union

    59 ::

    60 

    61     f10 | p10

    62 

    63 gives us the union of f10 and p10

    64 

    65 The & character stands for intersection.

    66 ::

    67 

    68     f10 & p10

    69 

    70 gives the intersection

    71 

    72 similarly,

    73 ::

    74 

    75     f10 - p10

    76 

    77 gives all the elements that are in f10 but not in p10

    78 

    79 ::

    80 

    81     f10 ^ p10

    82 

    83 is all the elements in f10 union p10 but not in f10 intersection p10. In

    84 mathematical terms, it gives the symmectric difference.

    85 

    86 {{{ Pause here and try out the following exercises }}}

    87 

    88 %% 1 %% Given a list of marks, marks = [20, 23, 22, 23, 20, 21, 23] 

    89         list all the duplicates

    90 

    91 {{{ continue from paused state }}}

    92 

    93 Duplicates marks are the marks left out when we remove each element of the 

    94 list exactly one time.

    95 

    96 ::

    97 

    98     marks = [20, 23, 22, 23, 20, 21, 23] 

    99     marks_set = set(marks)

   100     for mark in marks_set:

   101         marks.remove(mark)

   102 

   103     # we are now left with only duplicates in the list marks

   104     duplicates = set(marks)

   105 

   106 {{{ Show summary slide }}}

   107 

   108 This brings us to the end of the tutorial.

   109 we have learnt

   110 

   111  * How to make sets from lists

   112  * How to input sets

   113  * The various similarities with lists like length and containership

   114  * How to perform union, intersection and symmectric difference operations

   115 

   116 {{{ Show the "sponsored by FOSSEE" slide }}}

   117 

   118 #[Nishanth]: Will add this line after all of us fix on one.

   119 This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India

   120 

   121 Hope you have enjoyed and found it useful.

   122 Thankyou

   123  

   124 .. Author              : Nishanth

   125    Internal Reviewer 1 : 

   126    Internal Reviewer 2 : 

   127    External Reviewer   :