Review: Lists & Tuples

Module 2: Data Structures

Review of Session 2.1: Lists & Tuples

Exercise

After running this cell, what will be the contents of ls_numbers?

ls_numbers = []

for n in [1, 2, 3]:
  ls_numbers = [n] + ls_numbers
  # Remember you can add a print to see what is happening after every loop!
  # print(f"n = {n} in this loop")
  # print("After this loop the list is:", ls_numbers)

print(ls_numbers)

Exercise

After running this cell, what will be the contents of ls_numbers?

ls_numbers = []

for n in "one, two, three":
  ls_numbers.append(n)

print(ls_numbers)

Exercise

After running this cell, what will be the contents of ls_numbers?

ls_numbers = []

for n in range(2, 11, 2):
  if n == 6:
    continue
  ls_numbers.append(n)

print(ls_numbers)

Exercise

After running this cell, what will be the contents of ls_numbers?

ls_numbers = []

for n in range(10):
  ls_numbers.clear()
  ls_numbers.append(n)

print(ls_numbers)

Exercise

What will be the output of the following cell?

ls_boardgames = ["Monopoly", "Catan", "UNO"]

print(ls_boardgames[1][0])

::: {.callout-tip collapse=“true”} ## Solution In case of doubt, think about it one pair of brackets at a time:

:::
# First brackets
output_1 = ls_boardgames[1]
print(output_1)

# Second brackets
output_2 = output_1[0]
print(output_2)

Remember this works the same for tuples!

Exercise

What will be the output of the following cell?

tp_videogames = ("Pokemon", "Candy Crush", "FIFA", "Outer Wilds")

print(tp_videogames[1:3][1])

Exercise

What will be the output of the following cell?

tp_superheroes = ("Batman", "Ironman", "Superman")

print(tp_superheroes[2[1:4]])

Exercise

Which line is going to fail?

tp_colors = ("Blue",)
tp_colors = ("Green",) + tp_colors
tp_colors += ("Red,")
tp_colors.append("Yellow")

print(tp_aliens)

Exercise

Consider the following code. What will be the output?

numbers = [0, 1, 2, 3]
numbers = numbers.append(4)
print(numbers)

Solution

The answer is “None”. The append method modifies the list in-place and returns None. So, after this operation, the numbers list is modified to [0, 1, 2, 3, 4], and the result of numbers.append(4) is None.

If you want to print the modified list, you should do it in two steps:

numbers = [0, 1, 2, 3]
numbers.append(4)
print(numbers)

Exercise

After run this code, what will be the value of ls?

ls = ["Lucy", "Jack", "Alberto"]

ls.sort()
ls.insert(2, "Ben")

print(ls)

Exercise

After run this code, what will be the value of ls?

ls = ["Lucy", "Jack", "Alberto"]

ls.insert(2, "Ben")
ls.sort()

print(ls)

Exercise

After run this code, what will be the value of x?

ls = ["Lucy", "Jack", "Alberto"]

ls.insert(2, "Ben")

x = ls.sort()[0]

print(x)

Tuples

Exercise