10.1: Dictionary Basics

Learning Objectives

By the end of this section you should be able to

• Describe the structure of a dictionary object.
• Use type() to identify the type of a dictionary object.
• Explain why a dictionary object does not have duplicate key values.

Dictionaries

A dictionary in Python is a container object including key-value pairs. An example of a key-value item is a word in an English dictionary with its corresponding definition.

Checkpoint: Dictionaries

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Concepts in Practice: Dictionary basics

Given the dictionary object days = {"Sunday": 1, "Monday": 2, "Tuesday": 3}, answer the following questions.

1.

What are the keys in the days dictionary object?

1. "Sunday", "Monday", "Tuesday"

1, 2, 3

0, 1, 2

2.

What are the values in the days dictionary object?

1. 0, 1, 2
2. 1, 2, 3
3. "Sunday", "Monday", "Tuesday"

3.

What is the value associated with key "Sunday"?

1. "Sunday"
2. 1
3. 0

Dictionary type and properties

The dict type implements a dictionary in Python. Since a dictionary object is used to look up values using keys, a dictionary object cannot hold duplicate key values.

Checkpoint: Dictionary properties

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Concepts in Practice: Dictionary type and properties

Given the dictionary object encoding = {"a": 97, "b": 98, "A": 65, "B": 66}, answer the following questions.

4.

What does type(encoding) return?

1. dictionary

dict

str

5.

The encoding dictionary contains duplicate keys since it has both "a" and "A" as keys.

1. true
2. false

6.

A dictionary can have duplicate values.

1. true
2. false

Try It: Investigate variable types

Given the variables in the code below, examine the variables' types.

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