Hello friends and welcome to the tutorial on getting started with

lists

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

structure called lists .  We will learn :

How to create lists. 

Structure of lists .

Access list elements 

Append elements to lists 

Deleting elements from lists

I hope you have ipython running on your system .

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

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

order and there order has a meaning .

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

shell type ::

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

   <type 'list'>

This is an empty list without any elements .

* filled lists

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

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

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

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

List items need not all have the same data type.

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

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

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

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

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

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

We access list elements using the number of index . The

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

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

nonempty[3] the last element .::

	    nonempty[0] 

	    nonempty[1] 

	    nonempty[3]

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

   nonempty[-1] 

   nonempty[-2] 

   nonempty[-4]

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

 element .

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

append command .::

   nonempty.append('onemore') 

   nonempty.append(6) 

   nonempty

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

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

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

returns us 6.::

	 len(nonempty)

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

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

      del(nonempty[1])

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

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

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

shall be :: a.remove(100)

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

experiment . ::

	   a.append('spam') 

	   a 

	   a.remove('spam') 

	   a

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

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

and leaves others untouched .

{{{Slide for Summary }}}

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

We learned how to create lists .  

Append elements to list .

Delete Element from list.  

And Checking list length.

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This tutorial was created as a part of FOSSEE project.

I hope you found this tutorial useful.

Thank You

Author : Amit Sethi 

First Reviewer :