.. #[Puneeth: Fill in pre-requisites.]

Hello friends and welcome to the tutorial on Basic Data types and operators

in Python.

In this tutorial, we shall look at

.. #[Puneeth: Use double colon only for code blocks.]

.. #[Puneeth: include more details in the outline.]

  * int for integers

  * float for floating point numbers and 

  * complex for complex numbers

.. #[Puneeth: Changed to  int, float and complex.]

.. #[Puneeth: Loss of consistency. You talk of built-in data types, but

.. then you were calling them integers, floats and complex. Clean up

.. required.]

Now, we have our first integer variable a.

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,

.. #[Puneeth: Why are we suddenly talking of limits?

.. Something like this would be better. 

.. int data-type can hold integers of any size. for example - ]

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,

::

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.

.. #[Puneeth: again, the clean-up that I talked of above. Decide if you are

.. talking about the different type of numbers and the datatypes that are

.. used to represent them or if you are talking of the data-types and what

.. kind of numbers they represent. I think you should choose the former.]

Let us now look at the float data-type. 

Decimal numbers in python are represented by the float data-type ::

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.

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 ::

The results are self explanatory.

.. #[Puneeth: Why does booleans bring us to precedence? I don't see the

.. connection. Am I missing something?]

The usage of boolean brings us to an interesting question of precedence.

What if you want to apply one operator before another.

Lets write some piece of code to check this out.::

.. #[Puneeth: Consistency. In[]: is not present at other places.]

To check how precedence changes with parenthesis, we will try two

Let's now look at some operators available in Python to manipulate

these data types.

.. #[Puneeth: A mention of other operators would be good? Starting

.. with % and ** is a bit weird.]

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`. ::

Lets now discuss sequence data types in Python. Sequence data types

are those in which elements are kept in a sequential order. All the

elements accessed using index.

.. #[Puneeth: fix the last sentence - it sounds incomplete]

{{{ slide for memory aid }}}

The sequence datatypes in Python are ::

The list type is a container that holds a number of other objects, in the

given order.

Items enclosed in square brackets separated by comma constitutes a list.

Lists can store data of any type in them.

.. #[Puneeth: some continuity, when jumping to strings?]

Now we will have a look at strings

.. #[Puneeth: Contain's? That's not a word!]

.. #[Puneeth: Thus?]

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.

To create a tuple we use normal brackets '(' unlike '[' for lists.::

Because of their sequential property there are certain functions and

operations we can apply to all of them.

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'.

len function gives the length ::

Find maximum using max function and minimum using min::

.. #[Puneeth: Fix the sentence above. ]

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::

::

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.::

As you can see while the first command executes with out a problem there is

an error on the second one.

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:

Python has built in functions int, float and complex to convert one number

type data structure to another.

::

As you can see the decimal part of the number is simply stripped to get the

integer.::

In case of complex number to floating point only the real value of complex

number is taken.

However converting a string to a list and a list to a string is an

interesting problem. Let's say we have a string ::

This produces a list with the string split at whitespace. Similarly we can

split on some other character.

::