Python3 Data types 2

Python Data types 2.

PYTHON LIST :

List is an ordered sequence of items. It is most used datatype in Python and more Flexible.

 

  *  Declaring a list is, items Separated by commas( , ) are enclosed within brackets [ ].

  eg:      a=[10,'hello',10.3]

             print(a[1])                #print index element

               

       output: 'hello' 

*  Lists are mutable ,meaning ,elements in a list can be altered.

 

  eg:     a=[21,30.3,'list']

            print(a)

            a[1]=3.3

            print(a)

  

       output:    [21,30.3,'list']

                      [21,3.3,'list']

For more information suggested video

 https://youtu.be/e1ruxK_6XZY

PYTHON TUPLE :

 

   Tuple is an ordered sequence of items same as list. The only difference is that tuples are immutable, Tuples once created cannot be modified.

Declaring a tuple ,elements are separated by commas( , ) and enclosed within parentheses  ( ).

 

 eg:       b=(10,2.5,'tuple')

             print(b)

             print(b[2])

             b[1]=2.2

             print(b)

       output:  (10,2.5,'tuple')

                    'tuple'

                    ------------------------------------------------------------------                      

                    TypeError 

                    TypeError:  'tuple' object does not support item assignment.

PYTHON SET :

   Set is an unordered collection of unique items. Set is defined by values separated by comma( , ) inside braces { }. Items in a set are not ordered.

  eg:     a={1,2,3,4,5}

            print(a)

            print(type(a))

  

       output:  {1,2,3,4,5}

                      <class  ' set ' >

 *  We can also perform set operations like union ,intersection on two sets. Set have unique values.

 eg :       s={12,13,14,13,14}

              print(s)          #automatically set won't consider duplicate elements.

              print(s[1])       #we can't print particular element in set because it is unordered.

 

       output:  {12,13,14}

                     ---------------------------------------------------------------

                     TypeError

                     TypeError : 'set'  object does not support indexing.

PYTHON DICTIONARY :

         Dictionary is  an unordered collection of key-value pairs.

In Python, Dictionaries are defined within braces { } with each item being a pair in the form of key : value. key and value can be of any type.

  eg:       d={'a' : "apple", 'b' : "bat"}

              print(d['a'])

 

       output:   apple

CONVERSION BETWEEN DATATYPES :

    We can convert between different datatypes by using different type conversion functions like  int(), float(), str() etc.,

  eg:       float(4)

              int(2.5)

              str(21)

 

       output:   4.0

                       2

                       '21'

*  Conversion to and from string must contain compatible values.

 

  eg:       int('17g')

       output:   ------------------------------------------------------

                       --

                       ValueError

                      ValueError : invalid literal for int() with base 17 : '17g'

  eg:      user = "Rishitha"

             meters=100 

             print("Congrats," +user+"!You got selected for "+ str(meter)  +"meters running race competition.")

       output::   Congrats, Rishitha !You got selected for 100 meters running race competition.

*   Convert one sequence to another sequence:

  eg:      a=[2,3,4]

             print(type(a))

            #convert list of a to set 

             s=set(a)                        

             print(type(s))

           #convert string to list using list() method 

             list("hello")        

output :   < class  ' list' >

                 < class  'set' >

                  ['h', 'e', 'l', 'l', 'o']