6. Python 'Dict' Data Type


 

Dict (Dictionary)

We have covered about list, tuple, set, frozenset. But all these data types having one common point that is ‘all contain a group of single objects’. Like

The list contains a group of single objects within the square brackets,

The tuple contains a group of single objects within the round brackets or parenthesis,

The set contains a group of single objects within the curly braces,

The frozenset contains as a parenthesis with internal sets.

But sometimes our requirement is we want to represent key-value pairs.

Ex:      item number: item name

            Ticket number: person name

If we want to represent a group of objects as a key-value pair then we can using this data type. It’s called dict or dictionary. We all know that general English dictionary. The dictionary has a lot of English words and some words belonging to some meaning, dict data type also same like.

Example: Ticket number: person name.

Dict syntax is {1:one,2:two}.

Game_palyers = {cricket:rahul,chess:vishnu, tennis:sania}.

game_palyers = {1:'rahul',2:'vishnu',3:'sania'}

print(type(game_palyers))

<class 'dict'> #result

game_players = {1:'rahul',2:'vishnu',3:'sania'} #one type of create the dict

nice_players ={}            # another type of create the dict

nice_players[1] = 'rahul'

nice_players[2] = ' vishnu '

nice_players[3] = ' sania '

print(nice_players)

{1: 'rahul', 2: ' vishnu ', 3: ' sania '}   #result

python 3.6x version and before python 3 version dict data type not ordered type. But after 3.7 version dict data type is ordered type.

It’s most commonly used data type in python.

Now take this as example

game_players = {1:'rahul',2:'vishnu',3:'sania'} here 1 is key and ‘rahul’ is the value.

In 'dict' once we create the 'dict' data type we can’t change the keys and we can change the values. If we are trying to create like 

(game_players[1] = krishna) then it’s not showing any error.it’s replaced with rahul to krishna.

Now if you want to print the game_payers then it’s changed like

game_players = {1:'krishna',2:'vishnu',3:'sania'}

Imp points:

1.      Dict type represents a group of key-value pairs

2.     Dict type ordered after 3.7x version before it’s not an ordered type.

3.     Dict type not accepted duplicate keys but it’s accepted duplicate values.

4. Heterogeneous objects are allowed. Heterogeneous means all types of fundamental data types. 

5.     Dict type is mutable.

6.     Indexing and slicing not applicable.

 


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