Starting Out with Python, 3e Ch 9, Starting Out with Python, 3e Ch 7 (TEST)

This operator can be used to find the intersection of two sets. a. I b. & c. - d. ^

&

When you open a file for the purpose of retrieving a pickled object from it, what file access mode do you use?

'rb'

When you open a file for the purpose of saving a pickled object to it, what file access mode do you use?

'wb'

This operator can be used to find the difference of two sets. a. I b. & c. - d. ^

-

This is the first index in a list. a. - 1 b. 1 c. 0 d. The size of the list minus one

0

If you call the index method to locate an item in a list and the item is not found, this happens. a. A ValueError exception is raised. b. An Invalidindex exception is raised. c. The method returns - 1. d. Nothing happens. The program continues running at the next statement.

A ValueError exception is raised.

This will happen if you try to use an index that is out of range for a list. a. A ValueError exception will occur. b. An IndexError exception will occur. c. The list will be erased and the program will continue to run. d. Nothing-the invalid index will be ignored.

An IndexError exception will occur.

List

An object that contains multiple data items. Lists are mutable, which means that their contents can be changed during a program's execution.

How do you delete an element from a dictionary?

By using the del statement

How do you find the number of elements in a list?

By using the len Function. The len function takes the list as an argument and it returns the number of the elements present in the list .

How do you determine the number of elements that are stored in a dictionary?

By using the len function

A file object's writelines method automatically writes a newline ( '\n' ) after writing each list item to the file. T or F

False

A list can be a dictionary key. T or F

False

Assume list1 references a list. After the following statement executes, list1 and list2 will reference two identical but separate lists in memory: list2 = list1 T or F

False

Lists in Python are immutable. T or F

False

The dictionary method popitem does not raise an exception if it is called on an empty dictionary. T or F

False

The following statement creates an empty set: myset = ( ) T or F

False

The keys in a dictionary must be mutable objects. T or F

False

You can remove an element from a tuple by calling the tuple's remove method. T or F

False

You can store duplicate elements in a set. T or F

False

This operator can be used to find the union of two sets. a. I b. & c. - d. ^

I

What is the difference between the remove and discard methods?

If the specified element to delete is not in the set, the remove method raises a KeyError exception, but the discard method does not raise an exception.

insert(index, item) Method

Inserts an item into the list at the specified index.

What does the items method return?

It returns all a dictionary's keys and their associated values as a sequence of tuples.

What does the keys method return?

It returns all the 'keys' in a dictionary as a sequence of tuples.

What does the values method return?

It returns all the 'values' in the dictionary as a sequence of tuples.

An element in a dictionary has two parts. What are they called?

Key and value

Does a set allow you to store duplicate elements?

No

Give two reasons why tuples exist.

Processing a tuple is faster than processing a list. Tuples are safe. Because you are not allowed to change the contents of a tuple, you can store data in one and that data can not be modified (accidentally or otherwise) by any code in your program.

remove(item) Method

Removes the first occurrence of the item from the list. A ValueError exception is raised if the item is not found in the list.

index( item) Method

Returns the index of the first element whose value is equal to item. A ValueError exception is raised if item is not found in the list.

reverse() Method

Reverses the order of the items in the list.

______ a object is the process of converting the object to a stream of bytes that can be saved to a file for later retrieval.

Serializing

sort() Method

Sorts the items in the list so they appear in ascending order (from the lowest value to the highest value).

Which part of a dictionary element must be immutable?

The key

max Function

The max function accepts a sequence, such as a list, as an argument and returns the item that has the highest value in the sequence.

min Function

The min function accepts a sequence, such as a list, as an argument and returns the item that has the lowest value in the sequence.

What module do you import if you want to pickle objects?

The pickle module

What is the difference between the dictionary methods pop and popitem?

The pop method accepts a key as an argument, returns the value that is associated with that key, and removes that key-value pair from the dictionary. The popitem method returns a randomly selected key-value pair, as a tuple, and removes that key-value pair from the dictionary.

What is object serialization?

The process of converting the object to a stream of bytes that can be saved to a file for later retrieval.

When the * operator's left operand is a list and its right operand is an integer, the operator becomes this. a. The multiplication operator b. The repetition operator c. The initialization operator d. Nothing-the operator does not support those types of operands.

The repetition operator

Repetition Operator

The repetition operator makes multiple copies of a list and joins them all together. The star symbol is used, when the operand on the left side of the * symbol is a sequence (such as a list) and the operand on the right side is an integer, it becomes a repetition operator.

This is the last index in a list. a. 1 b. 99 c. 0 d. The size of the list minus one

The size of the list minus one

A list can be an element in another list. T or F

True

A tuple can be a dictionary key. T or F

True

Dictionaries are not sequences. T or F

True

Sets store their elements in an unordered fashion. T or F

True

The del statement deletes an item at a specified index in a list. T or F

True

The following statement creates an empty dictionary: mydct = { } T or F

True

The remove method raises an exception if the specified element is not found in the set. T or F

True

Tuples in Python are immutable. T or F

True

You can use the + operator to concatenate two lists. T or F

True

A Tuple does not support what methods?

Tuples do not support methods such as append, remove, insert, reverse, and sort.

Are the elements of a set ordered or unordered?

Unordered

How do you create an empty set?

You call the built-in set function.

How can you determine whether a key-value pair exists in a dictionary?

You can use the in operator to test for a specific key.

How can you determine whether a specific element exists in a set?

You can use the in operator to test for the element.

How do you determine the number of elements in a set?

You pass the set as an argument to the len function.

This operator can be used to find the symmetric difference of two sets. a. I b. & c. - d. ^

^

len Function

a built-in function that returns the length of a sequence, such as a list.

What is the primary difference between a list and a tuple?

a list is mutable, which means that a program can change its contents. a tuple is immutable, which means that once it is created, its contents cannot be changed.

two-dimensional list (nested lists)

a list that has other lists as its elements.

You can add one element to a set with this method. a. append b. add c. update d. merge

add

Sequence

an object that holds multiple items of data, stored one after the other. You can perform operations on a sequence to examine and manipulate the items stored in it.

This list method adds an item to the end of an existing list. a. add b. add to c. increase d. append

append

How do you find the lowest and highest values in a list?

by using the min and/or the max functions

in Operator

can be used to determine whether an item is contained in a list.

append(item) Method

commonly used to add items to a list. The item that is passed as an argument is appended to the end of the list's existing elements.

A ______ is an object that stores a collection of data. Each element in a dictionary has two parts: a key and a value. You use a key to locate a specific value.

dictionary

This set method removes an element but does not raise an exception if the element is not found. a. remove b. discard c. delete d. erase

discard

This term refers to an individual item in a list. a. element b. bin c. cubbyhole d. slot

element

The ____ dictionary method returns the value associated with a specified key. If the key is not found, it returns a default value. a. pop( ) b. key( ) c. value( ) d. get( )

get( )

You can use the ____ operator to determine whether a key exists in a dictionary. a. & b. in c. ^ d. ?

in

This is a number that identifies an item in a list. a. element b. index c. bookmark d. identifier

index

Tuple

is a sequence, very much like a list, but is an immutable sequence, which means that that once a tuple is created, its contents cannot be changed.

slice

is a span of items that are taken from a sequence. A slicing expression selects a range of elements from a sequence.

The ____ method returns all of a dictionary's keys and their associated values as a sequence of tuples. a. keys_values( ) b. values( ) c. items ( ) d. get( )

items ( )

This function returns the length of a list. a. length b. size c. len d. lengthof

len

The ____ function returns the number of elements in a dictionary: a. size( ) b. len( ) c. elements( ) d. count( )

len( )

The following function returns the number of elements in a set: a. size( ) b. len( ) c. elements( ) d. count( )

len( )

Built-in function to convert a tuple to a list

list ( )

This built-in function returns the highest value in a list. a. highest b. max c. greatest d. best of

max

Mutable

means their elements can be changed

Assume the following statement appears in a program: mylist = [ ] Which of the following statements would you use to add the string 'Labrador' to the list at index 0? a. mylist[0] = 'Labrador' b. mylist.insert(0, 'Labrador') c. mylist. append ( 'Labrador' ) d. mylist.insert('Labrador', 0)

mylist.insert(0, 'Labrador')

What function do you call to pickle an object?

pickle.dump

What function do you call to retrieve and unpickle an object?

pickle.load

In Python, object serialization is called ______

pickling

The ____ method returns the value associated with a specified key and removes that key-value pair from the dictionary . a. pop( ) b. random( ) c. popitem( ) d. rand_pop( )

pop( )

The ____ method returns a randomly selected key-value pair from a dictionary. a. pop( ) b. random( ) c. popitem( ) d. rand pop( )

popitem( )

This file object method returns a list containing the file's contents. a. to_list b. getlist c. readline d. readlines

readlines

This set method removes an element and raises an exception if the element is not found. a. remove b. discard c. delete d. erase

remove

del Statement

removes an element from a specific index, regardless of the item that is stored at that index.

A ______ contains a collection of unique values and works like a mathematical set.

set

This removes an item at a specific index in a list. a. the remove method b. the delete method c. the del statement d. the kill method

the del statement

You use ____ to delete an element from a dictionary. a. the remove method b. the erase method c. the delete method d. the del statement

the del statement

What is the difference between calling a list's remove method and using the del statement to remove an element?

the remove method is used to remove a specific element in a list. the del method is used to remove any element that is present at a specific index, regardless of what that element is.

Built-in function to convert a list to a tuple

tuple ( )

You can add a group of elements to a set with this method. a. append b. add c. update d. merge

update

Which of the following statements creates a tuple? a. values [1, 2, 3, 4] b. values {1, 2, 3, 4} c. values ( 1) d. values ( 1,)

values ( 1,)

You can use ____ to create an empty dictionary. a. { } b. ( ) c. [ ] d. empty( )

{ }