Python dictionaries

Python for MATLAB Users

Justin Kiggins

Product Manager

What is a dictionary?

Similar to a MATLAB structure array
Collection of key:value pairs
Ordering is not guaranteed

Retrieving data from a dictionary

type(definitions)

dict

print(definitions['aardvark'])

A nocturnal burrowing mammal with long ears, a tubular snout, and a long 
extensible tongue, feeding on ants and termites. Aardvarks are native to 
Africa and have no close relatives.

Creating dictionaries

# Create a dictionary
dog = {'name': 'Toby', 'breed': 'Basset Hound'}

Adding data to a dictionary

# Add more key:value pairs
dog['weight (lbs)'] = 552.3
dog['birthdate'] = "2016-06-26"
print(dog)

{'name': 'Toby',
 'breed': 'Basset Hound',
 'weight (lbs)': 552.3, 
 'birthdate': '2016-06-26'}

Updating dictionaries

# Update weight value
dog['weight (lbs)'] = 52.3

print(dog)

{'name': 'Toby',
 'breed': 'Basset Hound',
 'weight (lbs)': 52.3,
 'birthdate': '2016-06-26'}

Removing data from a dictionary

dog.pop('birthdate')
print(dog)

{'name': 'Toby',
 'breed': 'Basset Hound',
 'weight (lbs)': 52.3}

Let's practice!

Python for MATLAB Users