1 Hello friends and welcome to the tutorial on getting started with

     2 lists.

     3 

     4  {{{ Show the slide containing title }}}

     5 

     6  {{{ Show the slide containing the outline slide }}}

     7 

     8 In this tutorial we will be getting acquainted with a python data

     9 structure called lists.  We will learn ::

    10  

    11  * How to create lists

    12  * Structure of lists

    13  * Access list elements

    14  * Append elements to lists

    15  * Deleting elements from lists

    16 

    17 List is a compound data type, it can contain data of other data

    18 types. List is also a sequence data type, all the elements are in

    19 order and there order has a meaning.

    20 

    21 We will first create an empty list with no elements. On your IPython

    22 shell type ::

    23 

    24    empty = [] 

    25    type(empty)

    26    

    27 

    28 This is an empty list without any elements.

    29 

    30 * Filled lists

    31 

    32 Lets now define a list, nonempty and fill it with some random elements.

    33 

    34 nonempty = ['spam', 'eggs', 100, 1.234]

    35 

    36 Thus the simplest way of creating a list is typing out a sequence 

    37 of comma-separated values (items) between square brackets. 

    38 All the list items need not have the same data type.

    39 

    40 

    41 

    42 As we can see lists can contain different kinds of data. In the

    43 previous example 'spam' and 'eggs' are strings and 100 and 1.234

    44 integer and float. Thus we can put elements of heterogenous types in

    45 lists. Thus list themselves can be one of the element types possible

    46 in lists. Thus lists can also contain other lists.  Example ::

    47 

    48       list_in_list=[[4,2,3,4],'and', 1, 2, 3, 4]

    49 

    50 We access list elements using the number of index. The

    51 index begins from 0. So for list nonempty, nonempty[0] gives the

    52 first element, nonempty[1] the second element and so on and

    53 nonempty[3] the last element. ::

    54 

    55 	    nonempty[0] 

    56 	    nonempty[1] 

    57 	    nonempty[3]

    58 

    59 We can also access the elememts from the end using negative indices ::

    60    

    61    nonempty[-1] 

    62    nonempty[-2] 

    63    nonempty[-4]

    64 

    65 -1 gives the last element which is the 4th element , -2 second to last and -4 gives the fourth

    66 from last element which is first element.

    67 

    68 We can append elements to the end of a list using append command. ::

    69 

    70    nonempty.append('onemore') 

    71    nonempty

    72    nonempty.append(6) 

    73    nonempty

    74    

    75 As we can see non empty appends 'onemore' and 6 at the end.

    76 

    77 

    78 

    79 Using len function we can check the number of elements in the list

    80 nonempty. In this case it being 6 ::

    81 	 

    82 	 len(nonempty)

    83 

    84 

    85 

    86 Just like we can append elements to a list we can also remove them.

    87 There are two ways of doing it. One is by using index. ::

    88 

    89       del(nonempty[1])

    90 

    91 

    92 

    93 deletes the element at index 1, i.e the second element of the

    94 list, 'eggs'. The other way is removing element by content. Lets say

    95 one wishes to delete 100 from nonempty list the syntax of the command

    96 should be :: 

    97       

    98       a.remove(100)

    99 

   100 but what if their were two 100's. To check that lets do a small

   101 experiment. ::

   102 

   103 	   a.append('spam') 

   104 	   a 

   105 	   a.remove('spam') 

   106 	   a

   107 

   108 If we check a now we will see that the first occurence 'spam' is removed

   109 thus remove removes the first occurence of the element in the sequence

   110 and leaves others untouched.

   111 

   112 

   113 {{{Slide for Summary }}}

   114 

   115 

   116 In this tutorial we came across a sequence data type called lists. ::

   117 

   118  * We learned how to create lists.  

   119  * How to access lists.

   120  * Append elements to list.

   121  * Delete Element from list.  

   122  * And Checking list length.

   123  

   124 

   125 

   126 {{{ Sponsored by Fossee Slide }}}

   127 

   128 This tutorial was created as a part of FOSSEE project.

   129 

   130 I hope you found this tutorial useful.

   131 

   132 Thank You

   133 

   134 

   135  * Author : Amit Sethi 

   136  * First Reviewer : 

   137  * Second Reviewer : Nishanth