程序代写代做代考 python Starting Out with Python 4e (Gaddis)

Starting Out with Python 4e (Gaddis)
Chapter 9 Dictionaries and Sets

TRUE/FALSE

1. You would typically use a for loop to iterate over the elements in a set.

ANS: T

2. Sets are immutable.

ANS: F

3. Sets are created using curly braces { }.

ANS: F

4. The set remove and discard methods behave differently only when a specified item is not found in the set.

ANS: T

5. A dictionary can include the same value several times but cannot include the same key several times.

ANS: T

6. The union of two sets is a set that contains only the elements that appear in both sets.

ANS: F

7. The difference of set1 and aet2 is a set that contains only the elements that appear in set1 but do not appear in set2.

ANS: T

8. The elements in a dictionary are stored in ascending order, by the keys of the key-value pairs.

ANS: F

9. If you try to retrieve a value from a dictionary using a nonexistent key, a KeyError exception is raised.

ANS: T

10. The issubset() method can be used to determine whether set1 is a subset of set2.

ANS: T

MULTIPLE CHOICE

1. In a dictionary, you use a(n) __________ to locate a specific value.
a.
datum

b.
element

c.
item

d.
key

ANS: D

2. What is the correct structure to create a dictionary of months where each month will be accessed by its month number (for example, January is month 1, April is month 4)?
a.
{ 1 ; ‘January’, 2 ; ‘February’, … 12 ; ‘December’}

b.
{ 1 : ‘January’, 2 : ‘February’, … 12 : ‘December’ }

c.
[ ‘1’ : ‘January’, ‘2’ : ‘February’, … ’12’ : ‘December’ ]

d.
{ 1, 2,… 12 : ‘January’, ‘February’,… ‘December’ }

ANS: B

3. What will be the result of the following code?
ages = {‘Aaron’ : 6, ‘Kelly’ : 3, ‘Abigail’ : 1 }
value = ages[‘Brianna’]
a.
False

b.
-1

c.
0

d.
KeyError

ANS: D

4. What is the number of the first index in a dictionary?
a.
0

b.
1

c.
the size of the dictionary minus one

d.
Dictionaries are not indexed by number.

ANS: D

5. What is the value of the variable phones after the following code executes?
phones = {‘John’ : ‘5555555’, ‘Julie’ : ‘5557777’}
phones[‘John’] = 5556666′
a.
{‘John’ : ‘5555555’, ‘Julie’ : ‘5557777’}

b.
{‘John’ : ‘5556666’, ‘Julie’ : ‘5557777’}

c.
{‘John’ : ‘5556666’}

d.
This code is invalid.

ANS: B

6. Which would you use to delete an existing key-value pair from a dictionary?
a.
del

b.
remove

c.
delete

d.
unpair

ANS: A

7. Which would you use to get the number of elements in a dictionary?
a.
size

b.
length

c.
len

d.
sizeof

ANS: C

8. Which method would you use to get all the elements in a dictionary returned as a list of tuples?
a.
list

b.
items

c.
pop

d.
keys

ANS: B

9. Which method would you use to get the value associated with a specific key and remove that key-value pair from the dictionary?
a.
list

b.
items

c.
pop

d.
popitem

ANS: C

10. Which method can be used to add a group of elements to a set?
a.
add

b.
addgroup

c.
update

d.
addset

ANS: C

11. In order to avoid KeyError exceptions, you can check whether a key is in the dictionary using the __________ operator.
a.
included

b.
in

c.
isnotin

d.
isin

ANS: B

12. What does the get method do if the specified key is not found in the dictionary?
a.
It throws an exception.

b.
It does nothing.

c.
It returns a default value.

d.
You cannot use the get method to specify a key.

ANS: C

13. Which of the following does not apply to sets?
a.
The stored elements can be of different data types.

b.
All the elements must be unique; you cannot have two elements with the same value.

c.
The elements are unordered.

d.
The elements are in pairs.

ANS: D

14. What is the process used to convert an object to a stream of bytes that can be saved in a file?
a.
pickling

b.
streaming

c.
writing

d.
dumping

ANS: A

15. What will be displayed after the following code executes? (Note: the order of the display of entries in a dictionary are not in a specific order.)
cities = {‘GA’ : ‘Atlanta’, ‘NY’ : ‘Albany’, ‘CA’ : ‘San Diego’}
if ‘CA’ in cities:
del cities[‘CA’]
cities[‘CA’] = ‘Sacramento’
print(cities)
a.
{‘CA’: ‘Sacramento’}

b.
[‘CA’: ‘Sacramento’]

c.
{‘NY’: ‘Albany’, ‘GA’: ‘Atlanta’}

d.
{‘CA’: ‘Sacramento’, ‘NY’: ‘Albany’, ‘GA’: ‘Atlanta’}

ANS: D

16. What will be displayed after the following code executes? (Note: the order of the display of entries in a dictionary are not in a specific order.)
cities = {‘GA’ : ‘Atlanta’, ‘NY’ : ‘Albany’, ‘CA’ : ‘San Diego’}
if ‘FL’ in cities:
del cities[‘FL’]
cities[‘FL’] = ‘Tallahassee’
print(cities)
a.
{‘FL’: ‘Tallahassee’}

b.
KeyError

c.
{‘CA’: ‘San Diego’, ‘NY’: ‘Albany’, ‘GA’: ‘Atlanta’, ‘FL’ ‘Tallahassee’}

d.
{‘CA’: ‘San Diego’, ‘NY’: ‘Albany’, ‘GA’: ‘Atlanta’}

ANS: D

17. What will be displayed after the following code executes? (Note: the order of the display of entries in a dictionary are not in a specific order.)
cities = {‘GA’ : ‘Atlanta’, ‘NY’ : ‘Albany’, ‘CA’ : ‘San Diego’}
if ‘FL’ in cities:
del cities[‘FL’]
cities[‘FL’] = ‘Tallahassee’
print(cities)
a.
{‘FL’: ‘Tallahassee’}

b.
KeyError

c.
{‘GA’: ‘Atlanta’, ‘FL’: ‘Tallahassee’, ‘NY’: ‘Albany’, ‘CA’: ‘San Diego’}

d.
{‘CA’: ‘San Diego’, ‘NY’: ‘Albany’, ‘GA’: ‘Atlanta’}

ANS: C

COMPLETION

1. A(n) __________ is an object that holds multiple unique items of data in an unordered manner.

ANS: set

2. The built-in function, __________, returns the number of items in a set.

ANS: len

3. To add a single item to a set, you can use the set __________ method.

ANS: add

4. The __________ of two sets is a set that contains all the elements of both sets.

ANS: union

5. Each element in a(n) __________ has two parts: a key and a value.

ANS: dictionary

6. The elements in a dictionary are not stored in a specific order. Therefore, a dictionary is not a(n) ___________.

ANS: sequence

7. To determine whether or not a key is included in a dictionary, or if an element is included in a set, you can use the ___________ operator.

ANS: not in

8. The __________ method returns a value associated with a specific key and, if found, removes that key-value pair from the dictionary.

ANS: pop

9. The __________ method clears the contents of a dictionary.

ANS: clear

10. To write an object to a file, you use the __________ function of the __________ module.

ANS: dump, pickle

11. The __________ method returns all of a dictionary’s keys as a dictionary view.

ANS: keys

12. Each element in a dictionary view is a __________.

ANS: tuple