Dictionaries and Sets

Index page for Python:
http://mylearningcafe.blogspot.com/2015/08/python-index-page.html


Dictionaries in python are data structures which associate keys with values.

>>> empl_name_id_dict = {"Nitin":1,"Jonathan":2,"Brien":3}

>>> briens_details = empl_name_id_dict["Brien"]

>>> briens_details

3

>>> briens_details = empl_name_id_dict["brien"]

Traceback (most recent call last):

  File "<stdin>", line 1, in <module>

KeyError: 'brien'

Keys are case sensitive.

Get method helps to get a default value for a non-existing key rather than an exception

>>> briens_details = empl_name_id_dict.get("brien")

>>> briens_details

>>> 

>>> briens_details = empl_name_id_dict.get("Brien")

>>> briens_details

3

//Adding a new element

>>> empl_name_id_dict ["Matt"] = 4

>>> empl_name_id_dict

{'Nitin': 1, 'Matt': 4, 'Jonathan': 2, 'Brien': 3}

//Get the list of keys or values

>>> list_of_keys = empl_name_id_dict.keys()

>>> list_of_keys

['Nitin', 'Matt', 'Jonathan', 'Brien']

>>> 

>>> list_of_values = empl_name_id_dict.values()

>>> list_of_values

[1, 4, 2, 3]

>>> list_of_items = empl_name_id_dict.items()

>>> list_of_items

[('Nitin', 1), ('Matt', 4), ('Jonathan', 2), ('Brien', 3)]

Sets is a data structure that represents a collection of distinct elements.

>>> list_of_items = [1,100,200,3,100,200,5]

>>> list_of_items

[1, 100, 200, 3, 100, 200, 5]

>>> 

>>> list_of_items_set = set(list_of_items)

>>> list_of_items_set

set([200, 1, 3, 100, 5])

Index page for Python:

http://mylearningcafe.blogspot.com/2015/08/python-index-page.html