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 How to create lists. 

    11 Structure of lists .

    12 Access list elements 

    13 Append elements to lists 

    14 Deleting elements from lists

    15 

    16 I hope you have ipython running on your system .

    17 

    18 

    19 

    20 

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

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

    23 order and there order has a meaning .

    24 

    25 

    26 

    27 

    28 We will first create an empty list with no elements . On your ipython

    29 shell type ::

    30 

    31    In []: empty = [] In []: type(empty)

    32    

    33    <type 'list'>

    34 

    35 This is an empty list without any elements .

    36 

    37 * filled lists

    38 

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

    40 

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

    42 

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

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

    45 List items need not all have the same data type.

    46 

    47 

    48 As you can see lists can contain different kinds of data . In the

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

    50 integer and float . Thus you can put elements of heterogenous types in

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

    52 in lists.  Thus lists can also contain other lists in it .  Example ::

    53 

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

    55 

    56 

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

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

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

    60 nonempty[3] the last element .::

    61 

    62 

    63 	    nonempty[0] 

    64 	    nonempty[1] 

    65 	    nonempty[3]

    66 

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

    68    

    69    nonempty[-1] 

    70    nonempty[-2] 

    71    nonempty[-4]

    72 

    73 -1 being the last element , -2 second to last and -4 being the first

    74  element .

    75 

    76 * =append= elements We can append elements to the end of a list using

    77 append command .::

    78 

    79    nonempty.append('onemore') 

    80    nonempty.append(6) 

    81    nonempty

    82    

    83 As you can see non empty appends 'onemore' and 6 at the end

    84 

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

    86 nonempty .Because we just appended two elements at the end this

    87 returns us 6.::

    88 	 

    89 	 len(nonempty)

    90 

    91 Just like you can append elements to a list you can also remove them .

    92 Their are two ways of doing one is by index no. ::

    93 

    94       del(nonempty[1])

    95 

    96 deletes the element at index no.1 , i.e the second element of the

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

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

    99 shall be :: a.remove(100)

   100 

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

   102 experiment . ::

   103 

   104 	   a.append('spam') 

   105 	   a 

   106 	   a.remove('spam') 

   107 	   a

   108 

   109 If we check a now we will see that the first element spam is remove

   110 thus remove removes only the first instance of the element by sequence

   111 and leaves others untouched .

   112 

   113 

   114 {{{Slide for Summary }}}

   115 

   116 

   117 In this tutorial we came across a sequence data type called lists 

   118 We learned how to create lists .  

   119 Append elements to list .

   120 Delete Element from list.  

   121 And Checking list length.

   122 

   123 

   124 {{{ Sponsored by Fossee Slide }}}

   125 

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

   127 

   128 I hope you found this tutorial useful.

   129 

   130 Thank You

   131 

   132 

   133 Author : Amit Sethi 

   134 First Reviewer :