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Dictionary in Python

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June 21, 2017
Published By : Pratik Kataria
Categorised in:

  • Dictionary in Python is represented with key value pairs.
  • Keys must be unique whereas values are not.
  • Let’s understand some basics by example:
>>> a_dict = {}

>>> a_dict = { "abc" : "String 1" }

>>> a_dict

{'abc': 'String 1'}

>>> a_dict["abc"] = "String Change"

>>> a_dict

{'abc': 'String Change'}

>>> a_dict["abc"]

'String Change'

>>> a_dict[0] = "New dictionary item where key is integer"

>>> a_dict

{'abc': 'String Change', 0: 'New dictionary item where key is integer'}

>>> a_list = [1,2,3]

>>> a_dict['some_list'] = a_list

>>> a_dict

{'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3]}

>>> # above was putting a list inside dictionary

...

>>> # now putting a dictionary inside dictionary

...

>>> a_dict['dict_replica'] = a_dict

>>> a_dict

{'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {...}}

>>> a_dict["dict_replica"]

{'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {...}}

>>> # Hence, proving dictionaries can store all sorts of things. Cool and Weird.

...

>>> len(a_dict)

4

>>> str(a_dict)

"{'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {...}}"

>>> type(a_dict)

<class 'dict'>

>>> temp_dict = {"key": "value"}

>>> temp_dict

{'key': 'value'}

>>> temp_dict.clear()

>>> temp_dict

{}

>>> del temp_dict

>>> temp_dict

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

NameError: name 'temp_dict' is not defined

>>> a_dict.copy()

{'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {...}}}

>>> a_dict

{'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {...}}

>>> a_dict.items()

dict_items([('abc', 'String Change'), (0, 'New dictionary item where key is integer'), ('some_list', [1, 2, 3]), ('dict_replica', {'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {...}})])

>>> a_dict.keys()

dict_keys(['abc', 0, 'some_list', 'dict_replica'])

>>> temp_dict = {"key": "value"}

>>> a_dict.update(temp_dict)

>>> a_dict

{'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {...}, 'key': 'value'}

>>> a_dict.values()

dict_values(['String Change', 'New dictionary item where key is integer', [1, 2, 3], {'abc': 'String Change', 0: 'New dictionary item where key is integer', 'some_list': [1, 2, 3], 'dict_replica': {...}, 'key': 'value'}, 'value'])

>>>