Dictionaries vs. Lists

Dictionaries are similar to lists, but there are a few differences:

Both dictionaries and lists:

• are used to organize elements into collections;

• are used to initialize a new dictionary or list, use empty brackets;

• can iterate through the items or elements in the collection; and

• can use a variety of methods and operations to create and change the collections, like removing and inserting items or elements.

Dictionaries only:

• are unordered sets;

• have keys that can be a variety of data types, including strings, integers, floats, tuples;.

• can access dictionary values by keys;

• use square brackets inside curly brackets { [ ] };

• use colons between the key and the value(s);

• use commas to separate each key group and each value within a key group;

• make it quicker and easier for a Python interpreter to find specific elements, as compared to a list.

pet_dictionary = {"dogs": ["Yorkie", "Collie", "Bulldog"], "cats": ["Persian", "Scottish Fold", "Siberian"], "rabbits": ["Angora", "Holland Lop", "Harlequin"]}  


print(pet_dictionary.get("dogs", 0))
# Should print ['Yorkie', 'Collie', 'Bulldog']

Lists only:

• are ordered sets;

• access list elements by index positions;

• require that these indices be integers;

• use square brackets [ ];

• use commas to separate each list element.

pet_list  = ["Yorkie", "Collie", "Bulldog", "Persian", "Scottish Fold", "Siberian", "Angora", "Holland Lop", "Harlequin"]


print(pet_list[0:3])
# Should print ['Yorkie', 'Collie', 'Bulldog']