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+.. Objectives
+.. ----------
+
+.. Learn about Python Data Structures and Operators.(Remembering)
+.. Use them to do basic operations.(Applying)
+
+.. Prerequisites
+.. -------------
+
+
+     
+.. 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
+ * Operators in Python
+
+with a little hands-on on how they can be applied to the different data types.
+
+
+
+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 this }}}
+
+These are:
+
+  * Integers 
+  * float and 
+  * Complex 
+
+Lets first talk about integers. ::
+
+   a = 13
+   a
+
+
+Thats it, there we have our first integer variable a.
+
+
+
+If we now see ::
+     
+   type(a)
+   <type 'int'>
+
+This means that a is a type of int. Being an int data structure 
+in python means that there are various functions that this variable
+has to manipulate it different ways. You can explore these by doing,
+
+  a.<Tab>
+
+
+
+Lets see the limits of this int.
+
+  b = 99999999999999999999
+  b
+
+As you can see even when we put a value of 9 repeated 20 times 
+python did not complain. However when you asked python to print
+the number again it put a capital L at the end. Now if you check
+the type of this variable b, ::
+
+  type(b)
+  <type 'long'>
+
+
+The reason for this is that python recognizes large integer numbers
+by the data type long. However long type and integer type share there 
+functions and properties.
+
+Lets now try out the second type in list called float.
+
+Decimal numbers in python are recognized by the term float ::
+
+  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 aproximationation. 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.
+Lets check 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)
+
+
+
+{{ Slide for memory aid }} 
+
+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 explanotary in themselves.
+
+The usage of boolean brings us to an interesting question of precendence.
+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.
+
+  In[]: a=False 
+  In[]: b=True 
+  In[]: 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.
+
+
+Lets now look at some operators available in Python to manipulate these data types.
+
+
+
+Python uses % 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
+
+
+Lets now discuss sequence data stypes in python. Sequence 
+datatypes are those in which elements are kept in a sequential 
+order. All the elements accessed using index. 
+
+
+{{{ slide to for memory aid }}}
+
+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
+
+
+
+Now we will have a look at strings 
+
+type :: 
+
+ In[]: greeting_string="hello"
+
+
+greeting_string is now a string variable with the value "hello"
+
+{{{ Memory Aid Slide }}}
+
+Python strings can actually be defined in three different ways ::
+
+  In[]: k='Single quote'
+  In[]: l="Double quote contain's single quote"
+  In[]: m='''"Contain's both"'''
+
+Thus, 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.::
+
+  In[]: 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 ::
+
+  In[]: num_list[2]
+  In[]: num_list[-1]
+  In[]: greeting_string[1]
+  In[]: greeting_string[3]
+  In[]: greeting_string[-2]
+  In[]: num_tuple[2]
+  In[]: 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 ::
+
+     In[]: num_list+var_list
+     In[]: a_string="another string"
+     In[]: greeting_string+a_string
+     In[]: t2=(3,4,6,7)
+     In[]: num_tuple+t2
+
+len function gives the length  ::
+
+  In[]: len(num_list)
+  In[]: len(greeting_string)
+  In[]: len(num_tuple)
+
+Prints the length the variable.
+
+We can check the containership of an element using the 'in' keyword ::
+
+  In[]: 3 in num_list
+  In[]: 'H' in greeting_string
+  In[]: 2 in num_tuple
+
+We see that it gives True and False accordingly.
+
+Find maximum using max function and minimum using min:: 
+
+  In[]: max(num_tuple)
+  In[]: min(greeting_string)
+
+Get a sorted list and reversed list using sorted and reversed function ::
+
+  In[]: sorted(num_list)
+  In[]: reversed(greeting_string)
+
+As a consequence of the order one we access a group of elements together.
+This is called slicing and striding.
+
+First Slicing 
+
+Given a list ::
+
+  In[]:j=[1,2,3,4,5,6]
+
+Lets say we want elements starting from 2 and ending in 5.
+
+For this we can do ::
+
+  In[]: 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 notincluded in the resultant list::
+
+
+  In[]: j[:4]
+
+If first element is left blank default is from beginning and if last
+element is left blank it means till the end.
+
+ In[]: j[1:]
+
+ In[]: 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.::
+
+  In[]: new_num_list[1]=9
+  In[]: 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 ::
+
+  In[]: 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 string to list and list to string is an interesting problem.
+Lets 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.::
+
+  In[]:','.join['List','joined','on','commas']
+
+Thus we get a list joined on commas. Similarly we can do spaces.::
+
+  In[]:' '.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 .
+
+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.
+
+
+
+
+.. #[Nishanth]: string to list is fine. But list to string can be left for
+                string manipulations. Just say it requires some string 
+                manipulations and leave it there.
+
+.. #[Nishanth]: Where is the summary
+                There are no exercises in the script
+
+{{{ 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.
+
+
+