Chapter 4- Lists

Question 1

Indexing list

Answer 1

>>> spam = ['cat', 'bat', 'rat', 'elephant']
   >>> spam[0]
   'cat'
   >>> spam[1]
   'bat'
   >>> spam[2]
   'rat'
   >>> spam[3]
   'elephant'
   >>> ['cat', 'bat', 'rat', 'elephant'][3]
   'elephant'
➊ >>> 'Hello ' + spam[0]
➋ 'Hello cat'
   >>> 'The ' + spam[1] + ' ate the ' + spam[0] + '.'
   'The bat ate the cat.'

Question 2

A list is

Answer 2

list is a value that contains multiple values in an ordered sequence. The term list value refers to the list itself (which is a value that can be stored in a variable or passed to a function like any other value), not the values inside the list value.

Uses [ ]

Values inside the list are also called items. Items are separated with commas (that is, they are comma-delimited).

Question 3

List of other lists

Answer 3

>>> spam = [['cat', 'bat'], [10, 20, 30, 40, 50]]
>>> spam[0]
['cat', 'bat']
>>> spam[0][1]
'bat'
>>> spam[1][4]
50

Question 4

Negative indexing

Answer 4

> > > spam = [‘cat’, ‘bat’, ‘rat’, ‘elephant’]
spam[-1]
‘elephant’
spam[-3]
‘bat’
‘The ‘ + spam[-1] + ‘ is afraid of the ‘ + spam[-3] + ‘.’
‘The elephant is afraid of the bat.’

Question 5

Slicing lists

Answer 5

>>> spam = ['cat', 'bat', 'rat', 'elephant']
>>> spam[0:4]
['cat', 'bat', 'rat', 'elephant']
>>> spam[1:3]
['bat', 'rat']
>>> spam[0:-1]
['cat', 'bat', 'rat']

Question 6

Len()

What is length of
spam = [‘cat’, ‘bat’, ‘rat’, ‘elephant’]
2spam = [[‘cat’, ‘bat’], [10, 20, 30, 40, 50]

Answer 6

spam. len()

2spam. len()

Question 7

Asiago g values within lists

Answer 7

>>> spam = ['cat', 'bat', 'rat', 'elephant']
>>> spam[1] = 'aardvark'
>>> spam
['cat', 'aardvark', 'rat', 'elephant']
>>> spam[2] = spam[1]
>>> spam
['cat', 'aardvark', 'aardvark', 'elephant']
>>> spam[-1] = 12345
>>> spam
['cat', 'aardvark', 'aardvark', 12345]

Question 8

Del()

Answer 8

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

>>> spam = ['cat', 'bat', 'rat', 'elephant']
>>> del spam[2]
>>> spam
['cat', 'bat', 'elephant']
>>> del spam[2]
>>> spam
['cat', 'bat']

Question 9

Cat naming programming

Answer 9

Go review

Question 10

Iterating over a list

Answer 10

> > > supplies = [‘pens’, ‘staplers’, ‘flame-throwers’, ‘binders’]
for i in range(len(supplies)):
print(‘Index ‘ + str(i) + ‘ in supplies is: ‘ + supplies[i])

Question 11

Multiple variable assignment 
What'd easier than 
>> cat = ['fat', 'orange', 'loud']
>>> size = cat[0]
>>> color = cat[1]
>>> disposition = cat[2]

Answer 11

> > > cat = [‘fat’, ‘orange’, ‘loud’]

|&raquo_space;> size, color, disposition = cat

Question 12

Augmented variables

Answer 12

spam += 1
spam = spam + 1

spam -= 1
spam = spam - 1

spam *= 1
spam = spam * 1

spam /= 1
spam = spam / 1

spam %= 1
Spam =spam%1

Question 13

Methods

Answer 13

Called on values

Similar to functions

Question 14

Index()

First appearance is returned

Answer 14

>>> spam = ['hello', 'hi', 'howdy', 'heyas']
>>> spam.index('hello')
0
>>> spam.index('heyas')
3
>>> spam.index('howdy howdy howdy')
Traceback (most recent call last):
  File "", line 1, in 
    spam.index('howdy howdy howdy')
ValueError: 'howdy howdy howdy' is not in list

Question 15

Append()

Answer 15

> > > spam = [‘cat’, ‘dog’, ‘bat’]
spam.append(‘moose’)
spam
[‘cat’, ‘dog’, ‘bat’, ‘moose’]

Adds to the end of list

Question 16

Insert()

Answer 16

> > > spam = [‘cat’, ‘dog’, ‘bat’]
spam.insert(1, ‘chicken’)
spam
[‘cat’, ‘chicken’, ‘dog’, ‘bat’]

Question 17

Return value of insert(), append(),index()

Answer 17

None

So you do not want to have them assigned as variables

Question 18

Remove()

Answer 18

> > > spam = [‘cat’, ‘bat’, ‘rat’, ‘elephant’]
spam.remove(‘bat’)
spam
[‘cat’, ‘rat’, ‘elephant’]

Question 19

When do you use del() and when do you use remove()

Answer 19

Del() when you know index

Remove() when you know value

Question 20

Sort()

Answer 20

>>> spam = [2, 5, 3.14, 1, -7]
>>> spam.sort()
>>> spam
[-7, 1, 2, 3.14, 5]
>>> spam = ['ants', 'cats', 'dogs', 'badgers', 'elephants']
>>> spam.sort()
>>> spam
['ants', 'badgers', 'cats', 'dogs', 'elephants']

Question 21

Keyword for sort()

Answer 21

> > > spam.sort(reverse=True)
spam
[‘elephants’, ‘dogs’, ‘cats’, ‘badgers’, ‘ants’]

Question 22

3 things about sort()

Answer 22

1. no return value
2. cant sort integers and strings
3. sorts in ASCII betical order so uppercase comes before lower