Python Dictionaries 🍫

A dictionary is an unordered set of key:value pairs.

Dictionaries provide is a way to map pieces of data into eachother so that we can find values that are associated with one another.

Lets say we want to gather all of the calories in various candy bars 🍫

• Snickers 215 🍫

• Reese's 210 🍫

• KitKat 218 🍫

We can create a dictionary called chocolate to store this data:

chocolate = {'Snickers': 215, 'Reese's': 210, 'KitKat': 218}

1. A dictionary begins with curly brackets { }

2. Each of the keys are surrounded by quotations " " or '' and each key:value pairs are separated by a colon :

*** It is considered good practice to insert a space after each comma, although it will still run without the spacing. ( BUT don't worry it will still run without the spacing 😊 )

We can also create an empty dictionary:

empty_dict = {}

A single key:value pair can be added to the dictionary like this:

dict[key] = value

Try it yourself ! Open the replit and add a single key:value pair to our empty_dict we created.

Multiple key:value pairs can be added to a dictionary by using the .update() method

empty_dict = {'a':'alpha'}
empty_dict.update({'b':'beta','g':'gamma'})
print(empty_dict)

Output:

{'a':'alpha','b':'beta','g':'gamma'}

Syntax for overwriting existing values:

dictonary_name['key'] = value

Let's go back to our empty_dict example and change the value of 'a' from alpha ---> apple

empty_dict = {'a':'alpha','b':'beta','g':'gamma'}
empty_dict['a'] = apple
print(empty_dict)

Output:

{'a': 'apple ', 'b': 'beta', 'g': 'gamma'}