Data Science Portfolio

Dictionaries

Fundamentals

• A python dictionary represents a mapping between key-value pairs
• Key-value pairs can represent any combination of valid python objects
• Dictionaries are mutable, i.e. they can be modified

Build a dictionary using brackets

my_car = {'make': 'Nissan', 'model': 'Altima', 'year': 2010}

View the dictionary

my_car

{'make': 'Nissan', 'model': 'Altima', 'year': 2010}

Iterate through the dictionary

• Corresponding key and value can be retrieved simultaneously using items() method

for key, value in my_car.items():
    print('My car\'s ' + key + ' is: ' + str(value))

My car's make is: Nissan
My car's model is: Altima
My car's year is: 2010

Build a dictionary using keys

my_car = {}
my_car['make'] = 'Toyota'
my_car['model'] = 'Camry'
my_car['year'] = 2005

View the dictionary

my_car

{'make': 'Toyota', 'model': 'Camry', 'year': 2005}

Build a nested dictionary using brackets

my_cars = {'make': ['Nissan', 'Toyota'], 'model': ['Altima', 'Camry'], 'year': [2005, 2010]}

View the dictionary

my_cars

{'make': ['Nissan', 'Toyota'],
 'model': ['Altima', 'Camry'],
 'year': [2005, 2010]}

Index the first item of the list nested in the ‘year’ key

my_cars['year'][0]

2005

Remove a list element at a particular key

del my_cars['make'][1]

View the modified dictionary

my_cars

{'make': ['Nissan'], 'model': ['Altima', 'Camry'], 'year': [2005, 2010]}

Remove an entire key and its value

del my_cars['make']

View the modified dictionary

my_cars

{'model': ['Altima', 'Camry'], 'year': [2005, 2010]}

Empty all dictionary contents

my_cars.clear()

View the modified dictionary

my_cars

{}