Adding and deleting keys

There are many circumstances in which we may want to modify a dictionary that has already been created by adding or deleting key-value pairs. We will reference the same example dictionary class_dict in the following sections.

class_dict = {'instructors': 2, 'TAs': 10, 'tutors': 35, 'students': 600}

Adding Key-Value Pairs

We can add a key-value pair to an existing dictionary with the syntax:

dictionary[key] = value. Let’s add a new key-value pair to the example dictionary from above.

class_dict["head tutors"] = 3

Now, calling print(class_dict) will display this:

{'instructors': 2, 'TAs': 10, 'tutors': 35, 'students': 600, 'head tutors': 3}

Deleting Key-Value Pairs

We can delete key-value pairs from a dictionary with a little help from the del keyword. To delete the 'head tutors': 3 key-value pair we just added, we can run the line del class_dict["head tutors"]. Then, calling print(class_dict) will display this:

{'instructors': 2, 'TAs': 10, 'tutors': 35, 'students': 600}