Dictionaries allow data to be stored against a unique string key. This allows for relationships between values to be stored. Notation for dictionaries is with curly brackets {}, which items separated by commas, and key and values separated by colons ":". Dictionaries do not always retain order, this is depending on which version of python you use.
prices = {"apple":2.34, "pear":0.65, "chocolate": 1.34, "flour": 1.20, "eggs":2.99}
print (prices)
{'apple': 2.34, 'pear': 0.65, 'chocolate': 1.34, 'flour': 1.2, 'eggs': 2.99}
In this example we have created a list of shopping objects (keys) and paired them to a price.

Adding and Removing Items

items can be added by defining a value for a set key.
prices["bread"] = 1.20
print (prices)
{'apple': 2.34, 'pear': 0.65, 'chocolate': 1.34, 'flour': 1.2, 'eggs': 2.99, 'bread': 1.2}
Items can be removed with del similarly to lists.
del prices["pear"]
print (prices)
{'apple': 2.34, 'chocolate': 1.34, 'flour': 1.2, 'eggs': 2.99, 'bread': 1.2}

Common Methods

Two tools that help when working with dictionaries are the key() and value() methods. These create a list of keys and values, which can be useful when iterating over a dictionary.

print (prices.keys())
print (prices.values())
dict_keys(['apple', 'chocolate', 'flour', 'eggs', 'bread'])
dict_values([2.34, 1.34, 1.2, 2.99, 1.2])

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