Chapter 5 - Lists and dictionaries

Question 1

a list method to add something at the end of something else

Answer 1

scores.append(score) - adds score to the end of scores

Question 2

a list method to remove something based on value (unlike del. which deletes based on position)

Answer 2

scores.remove(score) - removes score

Question 3

sorts elements in a list (usually in ascending order - smallest values first)

Answer 3

sort()

reverse=True will sort in reverse order

Question 4

reverse()

Answer 4

reverses the order of a list

Question 5

count(value)

Answer 5

returns the number of occurrences of value

Question 6

returns the first position number where value occurs

Answer 6

index(value)

Question 7

inserts value at position i

Answer 7

insert(value, i)

Question 8

pop([i])

Answer 8

returns value at position i and removes the value from the list. Providing the position number i is optional. Without it the last element in the list is removed and returned.

Question 9

removes the first occurrence of value from the list

Answer 9

remove(value)

Question 10

Name 2-3 reasons to use tuples instead of lists

Answer 10

1. Tuples are faster than lists
2. Perfect for creating constants
3. Sometimes they are required

Question 11

nested sequences

Answer 11

sequences inside other sequences

Question 12

>>>name, age = ("Momchil", 21)
>>>print(name)
Momchil
>>>print(age)
21

Answer 12

unpacking (assigning each element to its own variable in a single line of code)

Question 13

What do variables do?

Answer 13

they are references to values, like a name is a reference to a person (they don’t contain the person)

Question 14

What is shared referencing?

Answer 14

Several variables referring to the same value (a change in the value results in a change in what all of the variables reference)

Question 15

What would the string language = “Python” do?

Answer 15

Store the string “Python” in the computer’s memory and then create the variable language, which will refer to that place in the memory

Question 16

>>> mike = ["khakis", "dress shirt", "jacket"]
>>> honey = mike[:]
>>> honey[2] = "red sweater"
>>> print(honey)
['khakis', 'dress shirt', 'red sweater']
>>> print(mike)
['khakis', 'dress shirt', 'jacket']

Answer 16

honey is assigned a copy of mike. honey does not refer to the same list, instead it refers to a copy. So a change to honey has no effect on mike.

Question 17

How do dictionaries store information

Answer 17

in items that consists of a key and a value