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+.. Objectives
+.. ----------
+
+.. At the end of this tutorial, you should know --
+
+.. 1. Learn about Python Data Structures and Operators.(Remembering)
+.. #.Use them to do basic operations.(Applying)
+
+.. Prerequisites
+.. -------------
+
+.. None
+     
+.. Author              : Amit Sethi
+   Internal Reviewer   : 
+   External Reviewer   :
+   Checklist OK?       : <put date stamp here, if OK> [2010-10-05]
+
+Hello friends and welcome to the tutorial on Basic Data types and operators
+in Python.
+
+{{{ Show the slide containing title }}}
+
+{{{ Show the slide containing the outline slide }}}
+
+In this tutorial, we shall look at
+
+* Datatypes in Python
+    * Numbers
+    * Boolean
+    * Sequence
+* Operators in Python
+  * Arithmetic Operators
+  * Boolean Operators
+
+* Python Sequence Data types
+  * list
+  * string
+  * tuple
+
+First we will explore python data structures in the domain of numbers.
+There are three built-in data types in python to represent numbers.
+
+{{{ A slide to make a memory note of the different datatypes }}}
+
+These are:
+
+  * int 
+  * float 
+  * complex 
+
+Lets first talk about int. ::
+
+   a = 13
+   a
+
+
+Now, we have our first int variable a.
+
+
+If we now see ::
+     
+   type(a)
+   <type 'int'>
+
+This means that a is a type of int. There are lot of functions associated
+with the int datatype, to manipulate it in different ways. These can be
+explored by doing, ::
+
+  a.<Tab>
+
+*int* datatype can hold integers of any size lets see this by an example.
+::
+
+  b = 99999999999999999999
+  b
+
+As you can see even when we put a value of 9 repeated 20 times python did
+not complain. This is because python's int data-type can hold integers of any
+size.
+
+Let us now look at the float data-type. 
+
+Decimal numbers in python are represented by the float data-type ::
+
+  p = 3.141592
+  p
+
+If you notice the value of output of ``p`` isn't exactly equal to ``p``.
+This is because computer saves floating point values in a specific format.
+There is always an approximation. This is why we should never rely on
+equality of floating point numbers in a program.
+
+The last data type in the list is complex number ::
+
+  c = 3.2+4.6j
+
+as simple as that so essentialy its just a combination of two floats the
+imaginary part being defined by j notation instead of i. Complex numbers
+have a lot of functions specific to them. Let us look at these ::
+
+  c.<Tab>
+
+Lets try some of them ::
+
+  c.real
+  c.imag
+
+c.real gives the real part of the number and c.imag the imaginary.
+
+We can get the absolute value using the function ::
+ 
+  abs(c)
+
+
+Following is are exercises that you must do. 
+
+%% %% Find the absolute value of 3+4j 
+::
+
+        abs(3+4j)
+
+%% %% What is the datatype of number 999999999999999999? Is it
+not int?
+::
+
+        Long
+        Big integers are internally stored in python
+        as Long datatype.  
+
+Please, pause the video here. Do the exercises and then continue. 
+
+
+{{ Slide for showing Boolean datatypes }} 
+
+Python also has Boolean as a built-in type.
+
+Try it out just type ::  
+
+  t = True
+
+note that T in true is capitalized.
+  
+You can apply different Boolean operations on t now for example ::
+
+  f = not t 
+  f
+  f or t
+  f and t 
+
+
+The results are self explanatory.
+
+What if you want to apply one operator before another.
+
+Well you can use parenthesis for precedence.
+
+Lets write some piece of code to check this out.::
+
+  a=False 
+  b=True 
+  c=True
+
+
+To check how precedence changes with parenthesis, we will try two
+expressions and their evaluation.
+
+one ::
+ 
+  (a and b) or c
+ 
+This expression gives the value True
+
+where as the expression :: 
+  
+  a and (b or c) 
+
+gives the value False.
+
+
+Let's now look at some operators available in Python to manipulate
+these data types.
+
+Python uses '+' for addition ::
+
+  23 + 74
+
+'-' for subtraction ::
+
+  23 - 56
+
+'*' for multiplication ::
+ 
+  45*76
+
+'/' for division ::
+    
+  384/16
+  8/3 
+  8.0/3
+
+When we did 8/3 the first case results in am integer 
+output as both the operands are integer however when 
+8.0/3 is used the answer is float as one of the operands is
+float. 
+
+
+'%' for modulo operation ::
+
+    87 % 6
+
+and two stars for a exponent. ::
+
+    7**8
+
+
+In case one wishes to use the current value of variable in which the result
+is stored in the expression one can do that by putting the operator before
+`equal to`. ::
+
+   a=73
+   a*=34
+
+is same as ::
+   
+   a=a*34
+
+and ::
+
+    a/=23
+
+is same as ::
+
+   a=a/23
+
+Following is are exercises that you must do. 
+
+%% %% Using python find sqaure root of 3?
+
+%% %% Is 3**1/2 and 3**0.5 same
+
+Please, pause the video here. Do the exercises and then continue.
+
+::
+
+   3**0.5
+
+::
+    No,One gives an int answer and the other float        
+
+
+Lets now discuss sequence data types in Python. Sequence data types
+are those in which elements are kept in a sequential order and all the 
+elements are accessed using index numbers.
+
+{{{ slide introducing sequence datatype }}}
+
+The sequence datatypes in Python are ::
+
+ * list
+ * string
+ * tuple
+
+The list type is a container that holds a number of other objects, in the
+given order.
+
+We create our first list by typing :: 
+  
+  num_list = [1, 2, 3, 4]
+  num_list
+
+
+Items enclosed in square brackets separated by comma constitutes a list.
+
+Lists can store data of any type in them.
+
+We can have a list something like ::
+
+ var_list = [1, 1.2, [1,2]]	
+ var_list
+
+Lets look at another sequence data type, strings
+
+type :: 
+
+  greeting_string="hello"
+
+
+greeting_string is now a string variable with the value "hello"
+
+{{{ All the different types of strings shown }}}
+
+Python strings can actually be defined in three different ways ::
+
+   k='Single quote'
+   l="Let's see how to include a single quote"
+   m='''"Let's see how to include both"'''
+
+As you can see, single quotes are used as delimiters usually.
+
+When a string contains a single quote, double quotes are used as
+delimiters. When a string quote contains both single and double quotes,
+triple quotes are used as delimiters.
+
+The last in the list of sequence data types is tuple.
+
+To create a tuple we use normal brackets '(' unlike '[' for lists.::
+
+   num_tuple = (1, 2, 3, 4, 5, 6, 7, 8)
+  
+Because of their sequential property there are certain functions and
+operations we can apply to all of them.
+
+
+
+The first one is accessing.
+
+They can be accessed using index numbers ::
+
+   num_list[2]
+   num_list[-1]
+   greeting_string[1]
+   greeting_string[3]
+   greeting_string[-2]
+   num_tuple[2]
+   num_tuple[-3]
+
+
+Indexing starts from 0 from left to right and from -1 when accessing lists
+in reverse. Thus num_list[2] refers to the third element 3. and greetings
+[-2] is the second element from the end , that is 'l'.
+
+
+
+Addition gives a new sequence containing both sequences ::
+
+      num_list+var_list
+      a_string="another string"
+      greeting_string+a_string
+      t2=(3,4,6,7)
+      num_tuple+t2
+
+len function gives the length ::
+
+   len(num_list)
+   len(greeting_string)
+   len(num_tuple)
+
+Prints the length the variable.
+
+We can check the containership of an element using the 'in' keyword ::
+
+   3 in num_list
+   'H' in greeting_string
+   2 in num_tuple
+
+We see that it gives True and False accordingly.
+
+Find maximum using max function and minimum using min::
+
+   max(num_tuple)
+   min(greeting_string)
+
+Get a sorted list  ::
+
+   sorted(num_list)
+   
+
+As a consequence of their order, we can access a group of elements in a
+sequence, together. This is called slicing and striding.
+
+First lets discuss Slicing, 
+
+Given a list ::
+
+  j=[1,2,3,4,5,6]
+
+Lets say we want elements starting from 2 and ending in 5.
+
+For this we can do ::
+
+   j[1:4]
+
+The syntax for slicing is, sequence variable name square bracket first
+element index, colon, second element index. The last element however is not
+included in the resultant list::
+
+
+   j[:4]
+
+If first element is left blank default is from beginning and if last
+element is left blank it means till the end.
+
+::
+
+  j[1:]
+
+  j[:]
+
+This effectively is the whole list.
+
+Striding is similar to slicing except that the step size here is not one.
+
+Lets see by example ::
+
+  new_num_list=[1,2,3,4,5,6,7,8,9,10]
+  new_num_list[1:8:2]
+  [2, 4, 6, 8]
+
+The colon two added in the end signifies all the alternate elements. This
+is why we call this concept striding because we move through the list with
+a particular stride or step. The step in this example being 2.
+
+We have talked about many similar features of lists, strings and tuples.
+But there are many important features in lists that differ from strings and
+tuples. Lets see this by example.::
+
+   new_num_list[1]=9
+   greeting_string[1]='k'
+
+{{{ slide to show the error }}}
+
+
+
+As you can see while the first command executes with out a problem there is
+an error on the second one.
+  
+Now lets try ::
+
+   new_tuple[1]=5
+
+Its the same error. This is because strings and tuples share the property
+of being immutable. We cannot change the value at a particular index just
+by assigning a new value at that position.
+
+
+We have looked at different types but we need to convert one data type into
+another. Well lets one by one go through methods by which we can convert
+one data type to other:
+
+We can convert all the number data types to one another ::
+
+  i=34
+  d=float(i)
+  d  
+
+Python has built in functions int, float and complex to convert one number
+type data structure to another.
+
+::
+
+  dec=2.34
+  dec_con=int(dec)
+  dec_con
+
+
+As you can see the decimal part of the number is simply stripped to get the
+integer.::
+
+  com=2.3+4.2j
+  float(com)
+  com
+
+In case of complex number to floating point only the real value of complex
+number is taken.
+
+Similarly we can convert list to tuple and tuple to list ::
+  
+  lst=[3,4,5,6]
+  tup=tuple(lst)
+  tupl=(3,23,4,56)
+  lst=list(tuple)
+
+However converting a string to a list and a list to a string is an
+interesting problem. Let's say we have a string ::
+
+  In: somestring="Is there a way to split on these spaces."
+  In: somestring.split()
+
+
+This produces a list with the string split at whitespace. Similarly we can
+split on some other character.
+
+::
+
+  In: otherstring="Tim,Amy,Stewy,Boss"
+
+How do we split on comma , simply pass it as argument ::
+
+  In: otherstring.split(',')
+
+join function does the opposite. Joins a list to make a string.::
+
+  ','.join['List','joined','on','commas']
+
+Thus we get a list joined on commas. Similarly we can do spaces.::
+
+  ' '.join['Now','on','spaces']
+
+Note that the list has to be a list of strings to apply join operation.
+
+With this we come to the end of this tutorial .
+
+Following is an (are) exercise(s) that you must do. 
+
+
+
+%% %% Check if 3 is an element of the list [1,7,5,3,4]. In case
+it is change it to 21.
+::
+        l=[1,7,5,3,4]
+        3 in l
+        l[3]=21
+        l
+
+%% %% Convert the string "Elizabeth is queen of england" to 
+"Elizabeth is queen"
+::
+
+           s="Elizabeth is queen of england"
+           stemp=s.split()
+           ' '.join(stemp[:3])
+   
+Please, pause the video here. Do the exercise(s) and then continue. 
+
+
+This brings us to the end of the tutorial. In this tutorial we have
+discussed
+
+1. Number Datatypes , integer,float and complex 
+2. Boolean and datatype and operators
+3. Sequence data types ,List,String and Tuple
+4. Accesing sequence
+5. Slicing sequences
+6. Finding length , sorting and reversing operations on sequences.
+7. Immutability.
+
+{{{ Show the "sponsored by FOSSEE" slide }}}
+
+This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India
+
+Hope you have enjoyed and found it useful.
+
+Thank You.
+
+
+.. 
+   Local Variables:
+   mode: rst
+   indent-tabs-mode: nil
+   sentence-end-double-space: nil
+   fill-column: 75
+   End: