Dictionaries in Python

 What is Dictionary


Creating a Dictionary

dict1={'fruits' : 'Apple', 'vegetable' : 'tomato'}

Example-1:

>>> dict1={'Fruits' : 'Apple', 'Vegetables' : 'Tomato'}
>>> dict1['Fruits']
'Apple'
>>> dict1['Vegetables']
'Tomato'

Note: Dictionaries are very flexible, that can hold any type of data types like integer, string, float, and etc.

Example-2: Collection of different data types

>>> SupperMarket={'Apple':2.50, 'Milk':1, 'Sugar':'Not Available', 'Stationary':['Pen','Pencil','Note Book']}
>>> SupperMarket['Milk']
1
>>> SupperMarket['Stationary']
['Pen', 'Pencil', 'Note Book']
>>> SupperMarket['Sugar']
'Not Available'

-- Call index on values on Dictionary

>>> SupperMarket={'Apple':2.50, 'Milk':1, 'Sugar':'Not Available', 'Stationary':['Pen','Pencil','Note Book']}
>>> SupperMarket['Stationary'][1]    ------------- index position 1 
'Pencil'

-- Call method on Dictionary 

>>> SupperMarket={'Apple':2.50, 'Milk':1, 'Sugar':'Not Available', 'Stationary':['Pen','Pencil','Note Book']}
>>> SupperMarket['Stationary'][1].upper()   ------- upper () method 
'PENCIL'

Let say Sugar is available in the Super Market and we need to update the item price. Here is an example

>>> SupperMarket={'Apple':2.50, 'Milk':1, 'Sugar':'Not Available', 'Stationary':['Pen','Pencil','Note Book']}
>>> SupperMarket
{'Apple': 2.5, 'Milk': 1, 'Sugar': 'Not Available', 'Stationary': ['Pen', 'Pencil', 'Note Book']}
>>> SupperMarket['Sugar']=1.75   ---------- updating the item's value
>>> SupperMarket
{'Apple': 2.5, 'Milk': 1, 'Sugar': 1.75, 'Stationary': ['Pen', 'Pencil', 'Note Book']} ------ Sugar value is updated


Nesting with Dictionary

Creating a nested dictionary (dictionary inside dictionary) and calling them. Here is an example:

Example:

>>> SupperMarket_Stationary={'Stationary':{'Price':{'Pen':0.75,'Pencil':0.50,'Note Book':2}}}
>>> SupperMarket_Stationary['Stationary']['Price']['Pencil']
0.5


Dictionary Methods

There are few dictionary methods available. Here are few examples.

  • keys
  • values
  • items
Examples:

>>> SupperMarket={'Apple':2.50, 'Milk':1, 'Sugar':'Not Available', 'Stationary':['Pen','Pencil','Note Book']}

>>> SupperMarket.keys()                    ----------- to list items available in SuperMarket 
dict_keys(['Apple', 'Milk', 'Sugar', 'Stationary'])

>>> SupperMarket.values()               ----------- to list prices available in SuperMarket 
dict_values([2.5, 1, 'Not Available', ['Pen', 'Pencil', 'Note Book']])

>>> SupperMarket.items()              ----------- to list all items & Prices available in SuperMarket 
dict_items([('Apple', 2.5), ('Milk', 1), ('Sugar', 'Not Available'), ('Stationary', ['Pen', 'Pencil', 'Note Book'])])



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