Dictionaries

A dictionary (https://docs.python.org/3.4/tutorial/datastructures.html#dictionaries) is a data type that is an unordered collection of key and value pairs. Each key in a dictionary has an associated value. An example of a dictionary is:

    >>> my_dict = {1: "Hello", 2: "World"}
    >>> my_dict

    {1: 'Hello', 2: 'World'}

A dictionary is created by using the braces {}. At the time of creation, new members are added to the dictionary in the following format: key: value (shown in the preceding example). In the previous example 1 and 2 are keys while 'Hello' and 'World' are the associated values. Each value added to a dictionary needs to have an associated key.

The elements of a dictionary do not have an order i.e. the elements cannot be retrieved in the order they were added. It is possible to retrieving the values of a dictionary by iterating through the keys. Let's consider the following example:

>>> my_dict = {1: "Hello", 2: "World", 3: "I", 4: "am...