W3 Basics - Lists

Question 1

What is a namespace

Answer 1

Mapping from names to objects.

For instance, two modules might have an attribute/method with the same name, but they are in different namespaces

module1.example module2.example module3

Question 2

I’ve created an object from a class. What can I add to the class to make the output of the below to be “Hi, my name is Jeff”

obj = Class()
print(obj)

Answer 2

def __str__(self):
return “Hello, my name is Jeff”

Question 3

Remove whitespace at beginning and end of string

Answer 3

string.strip()

Question 4

Replace H with J in Hello world

Answer 4

string.replace(‘H’, ‘J’)

Question 5

Turn string into a list separating elements by a ‘,’

Answer 5

string.split(‘,’)

Question 6

Using an f string, turn x = 55 in x = 55.00

add numbers in an fstring

Answer 6

print(f”{x:.2f} {22 + 50}”)

Question 7

Give a word double quotes with an escape character

Answer 7

“We are "vikings" today”

Question 8

Using an if statement see if ‘apple’ is in a list

Answer 8

if ‘apple’ in list:

if ‘apple’ not in list:

Question 9

Change second list item
If list has 6 elements, change the 2nd and 3rd item to ‘watermelon’ and ‘grape’

Answer 9

list[1] = ‘blue’
list[1:3] = [ ‘watermelon’, ‘grape’ ]

Question 10

If you insert more elements then your replace, what is the output:

thislist = [“apple”, “banana”, “cherry”]

thislist[1:2] = [“blackcurrant”, “watermelon”]

Answer 10

[‘apple’, ‘blackcurrant’, ‘watermelon’, ‘cherry’]

Question 11

Add list item ‘watermelon’ to a list with three entries. It should go in the second spot and erase the third entry

add ‘watermelon’ to the third spot using a method

Answer 11

list[1:3] = [‘watermelon’]

list.insert(2, ‘watermelon’)

Question 12

Append items in ‘tropical’ to ‘thislist’

Answer 12

thislist.extend(tropical)

If you append tuples or sets they’ll still come out as list items.

Question 13

There are four ways to delete lists
via string
2 via index
deleting the list itself
deleting all the list’s contents

Perform all of these steps

Answer 13

list.remove(‘’)
list.pop(2)
list.pop() removes last item
del list[2]
del list
list.clear()

Question 14

Using some python skills, create a loop that iterates through all list indices. Remember, you want to do this via INDICES

Answer 14

list = [‘this’, ‘that’, ‘other’]

for i in range(len(list)):
print(list[])

OR

i = 0
while i < len(list):
print(list[i]
i += 1

Question 15

Loop through a list using list comprehension

Answer 15

[print(x) for x in list]

Question 16

Using list comprehension, create a new list that only contains items that contain ‘a’ from ‘list’

Answer 16

[x for x in list if ‘a’ in x]

longer way
newlist = []
for x in (list):
if ‘a’ in x:
newlist.append(x)

Question 17

Using list comprehension, create a list of numbers 0 - 9

Do one that runs the same command, except only have it add items that are less than 5

Answer 17

[x for x in range(10)]

[x for x in range(10) if x < 5]

Question 18

Using list comprehension, change ‘banana’ to ‘orange’ in:

fruits = [“apple”, “banana”, “cherry”, “kiwi”, “mango”]

Answer 18

[x if x != ‘banana’ else ‘orange’ for x in fruits]

Question 19

Put your list in alphabetical/numeric order
Next sort them in reverse alphabetical/numeric order (different then just .reverse())

Answer 19

list.sort()
list.sort(reverse = True)

Question 20

Sort the list based on how close the number is to 50:

thislist = [100, 50, 65, 82, 23]

Answer 20

def myfunc(n):
return abs(n - 50)

thislist = [100, 50, 65, 82, 23]
thislist.sort(key = myfunc)

Question 21

Does sort sort capital or lower case letters first?

How would you use the sort method to turn everything into lowercase?

Answer 21

Capitals go before lowercase

list.sort(key = str.lower)

Question 22

Reverse the order of a list completely no matter the capitalization

Answer 22

list.reverse()

Question 23

Copy list into newlist
Do it via another method
Do it via a slice operator

Answer 23

newlist = list.copy()

mylist = list(list)

mylist = list[:]

Question 24

Add list2 to list1 in three different ways

Answer 24

list1.extend(list2)
list3 = list1 = list2
for i in list2:
list1.append(i)