sweigart chapter 4

Question 1

list

Answer 1

a value that contains multiple values in an ordered sequence. a list begins with an opening square bracket and ends with a closing square bracket.

Question 2

list value

Answer 2

refers to the list itself, not the values inside the list.

Question 3

items

Answer 3

values inside the list. they are separated with commas (comma-delimited).

Question 4

index

Answer 4

the integer inside the square brackets that follows the list, eg. spam[0].

Question 5

slice

Answer 5

can get several values from a list, in the form of a new list. it is typed between square brackets like an index, but it has 2 integers separated by a colon [:]. the first integer is the index where the slice starts, the second integer is where it ends. it goes up to but does not include the value at the second index.

Question 6

del statement

Answer 6

will delete values at an index in a list. all of the values in the list after the deleted value will be moved up one index. it can also be used to delete a variable, as id it were an “unassignment” statement.

Question 7

in and not in operators

Answer 7

can be used to determine whether a value is or isn’t in a list. they are used in expressions and connect two values: a value to look for in a list and the list where it may be found. these expressions will evaluate to a Boolean value.

Question 8

multiple assignment trick/tuple unpacking

Answer 8

a shortcut that lets you assign multiple variables with the values in a list in one line of code. the number of variables and the length of the list must be exactly equal.

Question 9

enumerate () function

Answer 9

on each iteration of the loop, the function will return two values: the index of the item in the list and the item in the list itself. the function is useful if you need both the item and the item’s index in the loop’s block. it can be used instead of the range(len(someList)) technique with a for loop.

Question 10

random.choice() function

Answer 10

will return a randomly selected item from the list.

Question 11

random.shuffle() function

Answer 11

will reorder the items in a list. this function modifies the list in place, rather than returning a new list.

Question 12

augment assignment operator

Answer 12

eg. +=, which can be used as a shortcut.

Question 13

method

Answer 13

the same thing as a function, except it is “called on” a value. each data type has its own set of methods. eg. if a list value were stored in spam, you would call the index() list method on that list like so: spam.index(‘hello’).

Question 14

append() method

Answer 14

adds an argument at the end of the list.

Question 15

insert() method

Answer 15

an insert a value at any index in the list. the first argument to insert() is the index for the new value, and the second argument is the new value to be inserted.

Question 16

remove() method

Answer 16

removes value from the list. if the value appears multiple times in the list, only the first instance of the value will be removed.

Question 17

index() method

Answer 17

used to find a value in a list. if the value exists in the list, the index of the value is returned. if not, Python produces an error.

Question 18

sort() method

Answer 18

used to sort the number values or strings in a list. values can also be sorted in reverse order by passing True for the reverse keyword argument.

Question 19

ASCIIbetical order

Answer 19

means that uppercase letters come before lowercase letters. this is used for sort().

Question 20

str.lower

Answer 20

passed for the key keyword argument in a sort() method call to sort values in regular alphabetical order.

Question 21

reverse() method

Answer 21

used to reverse values in a list.

Question 22

line continuation character ()

Answer 22

used to split up a single instruction across multiple lines. it says “This instruction continues on the next line”.

Question 23

string

Answer 23

can be considered as a “list” of single test characters.

Question 24

mutable data type

Answer 24

can have values added, removed, or changed, eg. a list value.

Question 25

immutable data type

Answer 25

cannot be changed, eg. a string.

Question 26

tuple data type

Answer 26

almost identical to the list data type, except (1) they are typed with parentheses instead of square brackets, and (2) they are immutable. if you only have one value in your tuple you can indicate this by placing a trailing comma (,) after the value inside the parentheses.

Question 27

variables

Answer 27

technically, variables store references to the computer memory locations where values are stored.

Question 28

id() function

Answer 28

used to obtain the unique identity of values. the numeric memory address where the string is stored is returned by the id() function. this address is based on which memory bytes happen to be free on your computer at the time, so it’ll be different each time you run this code.

Question 29

append() method

Answer 29

changes the existing list object and does not create a new list object. this is called “modifying the object in-place”.

Question 30

automatic garbage collector

Answer 30

Python has an automatic garbage collector that deletes any values not being referred to by an variables to free up memory.

Question 31

copy() function

Answer 31

copy.copy() can be used to make a duplicate copy of a mutable value like a list or dictionary, not just a copy of a reference. this way, variables will refer to separate lists.

Question 32

deepcopy() function

Answer 32

copy.deepcopy() is used instead of copy.copy() if the list you need to copy contains lists.