Dictionary keys cannot be list:

• In Python, a dictionary is defined as an unordered collection of data.

• Each element of the dictionary is a key-value pair.

• For each key, there is a value mapped to it.

• The keys in dictionary cannot be modified but the values can be modified.

• Keys in the dictionary must be immutable objects.

○ Immutable object:

■ An object that cannot be modified after its creation is the immutable object.

■ Examples of immutable objects are list, array, set, and so on.

○ Mutable object:

■ An object that can be modified after its creation is the mutable object.

■ Examples of mutable objects are integer, float, string, and so on.

• List is a mutable object since the elements in the list can be modified.

• Since list is mutable object, list cannot be a dictionary key.

Syntax:

In Python, the syntax to create the dictionary is as follows:

dictionary_name={key1:value1,key2:value2…}

In the above syntax,

• A dictionary can have multiple elements...

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Chapter 9, Problem 3TF

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Chapter 9 Solutions

Starting Out with Python (4th Edition)

Ch. 9.1 - An element in a dictionary has two parts. What are...Ch. 9.1 - Which part of a dictionary element must be...Ch. 9.1 - Suppose ' start' : 1472 is an element in a...Ch. 9.1 - Suppose a dictionary named employee has been...Ch. 9.1 - What will the following code display? stuff = {1 :...Ch. 9.1 - Prob. 6CP Ch. 9.1 - Suppose a dictionary named inventory exists. What...Ch. 9.1 - What will the following code display? stuff = {1 :...Ch. 9.1 - What will the following code display? stuff = {1 :...Ch. 9.1 - What is the difference between the dictionary...

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Solution Summary: The author explains that a dictionary is an unordered collection of data. Each element of the dictionary consists of key-value pairs and mutable objects.

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