* Data Types

*** Outline

***** Introduction

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    Welcome friends. 

    In this tutorial we shall look at data types in Python and 

    mathematical operators available.

    For 'Numbers' we have: int, float, complex datatypes    

    For conditional statements, 'Booleans'.

    Lets get started by opening IPython interpreter. 

    Lets start with  'numbers'

    x = 13

    print x

    To check the data type of any variable Python provides 'type' function

    type(x)

    lets create one more variable

    y = 999999999999

    print y

    Floating point numbers come under 'float'

    p = 3.141592

    type(p)

    Python by default provides support for complex numbers. 

    c = 3+4j 

    creates a complex number c. Here 'j' is used to specify the imaginary 

    part.

    type(c)

    Python also provides basic functions for their manipulations like

    c.imag returns imaginary part and c.real gives the real part. 

    All the basic operators work with Python data types, without any

    surprises. When we try to add two numbers like x and y Python takes 

    x + y

    Same as additions multiplication also works just right:

    3124 * 126789

    396088836

    Division in Python truncates, that is, when we divide a integer 

    variable with another integer result is also integer and decimal 

    value is truncated. So

    17 / 2 returns 8 and not 8.5

    but

    17 / 2.0 will return the correct 8.5, similarly

    17.0 / 2 will also give correct answer.

    Other operators which comes handy are:

    += 

    lets create one variable a with

    a =  7546

    now

    a += 1 will increment the value of 'a' by 1

    similarly 

    a -= 1 will decrement.

    we can also use 

    a 

    a /= 5    

    a is divided by 5

    Next we will look at Boolean datatype:

    Its a primitive datatype having one of two values: True or False.

    t = True

    print t

    Python is case sensitive language, so True with 'T' is boolean type but

    true with 't' would be a variable. 

    f = not True

    f or t

    f and t

    a = False

    b = True

    c = True

    (a and b) or c    

    True

    first a and b is evaluated and then the 'or' statement

    a and (b or c)

    False

    We also have support for relational and logical operators. Lets try some

    examples:

    We start with initializing three variables by:

    p, z, n = 1, 0, -1 

    To check equivalency of two variables use '=='

    p == z 

    False

    p >= n

    True

    We can check for multiple logical operations in one statement itself.

    n < z < p

    True.

    This statement checks if 'z' is smaller then 'p' and greater then 'n'

    For inequality testing we use '!'

    We have already covered briefly in some of the previous sessions, 

    conversion of data among different types.

    int(17 / 2.0) will convert result to integer type and we get

    8 as answer and not 8.5

    But if we try something like 

    float(17 / 2) we get 8.0 as 17/2 is already truncated to int

    and converting that to float wont restore the lost decimal digits.

    This brings us to the end of tutorial on introduction of Data types 

    related to numbers in Python. In this tutorial we have learnt what are 

    supported data types for numbers, operations and operators and how to 

    convert one data type to other. Thank you!

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