Ch. 9: Dictionaries and Sets

After executing, what will the following code print? >>>phonebook = {'Chris':'555−1111', 'Katie':'555−2222', 'Joanne':'555−3333' >>>for key in phonebook: print(key, phonebook[key])

Chris 555-1111 Joanne 555-3333 Katie 555-2222

T/F: Dictionaries are NoT mutable objects.

F

T/F: In a dictionary, keys cannot be of different types.

F

T/F: Keys can be lists or any other type of immutable object?

F

T/F: The following codes are equal: phonebook['sameer'] and phonebook['Sameer']

F

T/F: When using dictionaries, you can use a numeric index to retrieve a value by its position from a dictionary?

F

T/F: Dictionaries are NOT sequences.

T

T/F: String comparisons are case sensitive.

T

T/F: The keys in a dictionary must be immutable objects, but their associated values can be any type of object.

T

T/F: You cannot have duplicate keys in a dictionary.

T

What error code will occur given the following code: >>>phonebook ={'Chris':'555-1111', 'Katie':'555-2222', 'Joanne':'555-3333'} >>>phonebook['Kathryn']

a KeyError

When you want to retrieve a value from a dictionary, what code do you use?

a key

What are the two parts of a dictionary?

a key and a value

Which part of a dictionary element must be immutable?

all of it

What is a dictionary?

an object that stores a collection of data

What function clears the contents of a dictionary

clear()

Using the general format, how can you delete an existing key-value pair from a dictionary?

del dictionary_name[key]

Other than using dictionary_name = {} to create a blank dictionary, how else could you create an empty dictionary?

dictionary_name = dict()

How do you create an empty dictionary?

dictionary_name = {}

What is the general format to retrieve a value from a dictionary?

dictionary_name[key]

Using the general format, how can you add new key-value pairs to a dictionary?

dictionary_name[key] = value

In the general format, what code allows you to iterate over all the keys in a dictionary?

for var in dictionary:

What function gets the value associated with a specified key? If the key is not found, the method does not raise an exception. Instead, it returns a default value.

get(key, default)

How can you prevent a KeyError exception from being raised when you are searching a dictionary to determine whether a key exists within the dictionary? (Write the example code for your answer.)

if 'keyYouWantToFind" in phonebook: print(phonebook['keyYouWantToFind'])

What function returns all the keys in a dictionary and their associated values as a sequence of tuples?

items()

What function returns all the keys in a dictionary as a sequence of tuples?

keys(key, default)

What built-in python function can you use to get the number of elements in a dictionary?

len()

key-value pairs are often referred to as what?

mappings

What function returns the value associated with a specified key and removes that key-value pair from the dictionary? If the key is not found, the method returns a default value.

pop()

What function returns a randomly selected key-value pair as a tuple from the dictionary and removes that key-value pair from the dictionary.

popitem()

Element --- 'start' : 1472 ---- is an element in a dictionary. What is the key? What is the value? (answer key comma space value)

start, 1472

What is a key used for?

to locate a specific value

What function returns all the values in the dictionary as a sequence of tuples.

values()

In a dictionary, when can keys be of different types.

when they are immutable

How do you create a dictionary?

{}