10.1: Dictionary Basics
- Page ID
- 117585
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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.
Given the dictionary object days = {"Sunday": 1, "Monday": 2, "Tuesday": 3}, what are the keys in the days dictionary object?
"Sunday", "Monday", "Tuesday"1, 2, 30, 1, 2
- Answer
-
a. The first item in each key-value pair is the key. Hence
"Sunday", "Monday", "Tuesday"are key items.
What are the values in the days dictionary object?
0, 1, 21, 2, 3"Sunday", "Monday", "Tuesday"
- Answer
-
b. The second item in each key-value pair is the value. Hence
1, 2, 3are value items.
What is the value associated with key "Sunday"?
"Sunday"10
- Answer
-
b. Based on the
daysdictionary object, the value assigned to"Sunday"is1.
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.
Given the dictionary object encoding = {"a": 97, "b": 98, "A": 65, "B": 66}, answer the following questions.
Given the dictionary object encoding = {"a": 97, "b": 98, "A": 65, "B": 66}, answer the following questions.
type(encoding) return?
dictionarydictstr
- Answer
-
b. The type of a dictionary object is
dict.
The encoding dictionary contains duplicate keys since it has both "a" and "A" as keys.
- true
- false
- Answer
-
b. A dictionary cannot have duplicate keys, and
"a"and"A"are two different keys because"a"and"A"are different characters.
A dictionary can have duplicate values.
- true
- false
- Answer
-
a. A dictionary can have duplicate values, but not duplicate keys.
Given the variables in the code below, examine the variables' types.
- Answer
-
var_1 = ["a1", "b2", "c3"]var_2 = {"a": 1, "b": 2, "c": 3}print(type(var_1))print(type(var_2))