Python: Working with Dictionaries

A dictionary is an advanced data structure in Python. It holds data in a Key – Value combination.

Basic Syntax for a dictionary:

dictionary = { <key> : <value>,
               <key> : <value>,
               <key> : <value> }

I think the key/value relationship can be explained thinking about a car. A car has a few key values that describe it. Think: make, model, color, year

If I want to make a dictionary to describe a car, I could build it like this:

car = { 'Make': 'Ford',
        'Model': 'Mustang',
        'Color': 'Candy Apple Red',
        'Year': 1965 }

You can also use the dict() function to create a dictionary

car = dict([ ('Make', 'Ford'), 
             ('Model', 'Mustang'),
             ('Color', 'Candy Apple Red'),
             ('Year', 1965)])

Now, how do we access the values in a dictionary. I know in lists you can just refer to the index, but in dictionaries, it doesn’t work that way.

  

Instead, we refer to dictionaries by their key:

You can add a key/value pair:

You can change a dictionary value:

To remove values from a dictionary, use the del() function

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