Question

explain dictionary in python​

Answer 1

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Dictionary in python have a "key" and a "value of the key".That is, python dictionaries are the collection of key:value pairs.

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Answer 2

Heya friend,

Here we go :

Definition :

Python dictionary is an unordered collection of items where each item is a key - value pair. Dictionary can also be considered as a mapping between a set of keys/indices and set of values.

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Important features :

• Each key map to a value. The association of a key and a value is called a key - value pair.
• Each key is separated from it's value by a colon (:) , the items are separated by commas, and the entire dictionary is enclosed in curly braces {} .
• Keys are unique within a dictionary while values may not be.
• The value of a dictionary can be of any type, but the keys must be of an immutable data type such as strings, numbers or tuples.
• Dictionary is mutable. We can add new items or change the value of existing items.

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Creating a dictionary :

A dictionary can be created by placing the items (i.e. the key - value pair) inside curly braces {} separated by comma.

Syntax:

<dictionary_name> = {'key1' : 'value1' , 'key2' : 'value2' , 'key3' : 'value3' ,'keyn' : 'valuen' }

Example:

d = {'manav' : 'python' , 'manav1' : 'dictionary' , 'manav2' : 'tuple'}

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Methods to create a dictionary:

> To create an empty dictionary

d1 = {}                                                        

print(d1)

{}

> To create a dictionary directly using curly braces

d2 = {'A' : '1' , 'B' : '2' , 'C' : '3' }

print(d2)

{'A' : '1' , 'B' : '2' , 'C' : '3' }

> To create a dictionary using dict() function

d3=dict()

print(d3)

{}

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Accessing elements in a dictionary

[ To access dictionary elements, we can use square brackets along with the key to obtain it's value ]

d = {'A' : '1' , 'B' : '2' , 'C' : '3' }

print(d['A'])

1

Now, if we give a command like :

d = {'A' : '1' , 'B' : '2' , 'C' : '3' }

print(d['A'])

KEY ERROR                         [Because the key is not a part of the dictionary]

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List of functions which can be used in a dictionary :-

• len () - calculates number of key-value pair in a dictionary.
• clear() - removes all items from a dictionary.
• get() method - returns the value for a given key, if key is not available, it then returns the default value None.
• items() - gives the content of dictionary as a list of tuples having key - value pairs enclosed within round braces ().
• keys() - returns list of key in a dictionary enclosed within round braces ().
• values() - returns list of value in a dictionary enclosed within round braces ().

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Thanks !

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@MANAV