Tuples Worksheet

Problem 1

Write a function tuple_cat that takes as argument a tuple and returns a new tuple with one more element: the string 'cat'.

Examples:

tuple_cat((1, 2)) returns tuple (1, 2, 'cat')
tuple_cat(("A", "B", "C")) returns tuple ('A', 'B', 'C', 'cat')

Hint: Use tuple concatenation!

# Your code here

assert tuple_cat((1,)) == (1, 'cat')
assert tuple_cat((1, 2)) == (1, 2, 'cat')
assert tuple_cat((0, 0, 0, 0)) == (0, 0, 0, 0, 'cat')

Problem 2

Write a function swap_elements that takes one argument, a list. Your function should swap the first and last elements of the list in place, returning nothing.

Hint: Use multiple assignment to swap, e.g.:

a, b = b, a

# Your code here

L = [1, 2, 3]
assert swap_elements(L) is None
assert L == [3, 2, 1]
L.append(0)
assert swap_elements(L) is None
assert L == [0, 2, 1, 3]
L.append(5)
assert swap_elements(L) is None
assert L == [5, 2, 1, 3, 0]

Problem 3

Write a function count_six_seven that takes one argument: a list of integers. Determine which of the integers 6 or 7 appears more frequently in the list. You can assume that one of them will appear more frequently than the other. Return a tuple: the first element of the returned tuple is the int 6 or 7, and the second element of the returned tuple is how many times it appears.

Examples:

count_six_seven([1, 6, 1, 7, 6]) returns tuple (6, 2)
count_six_seven([7]) returns tuple (7, 1)
count_six_seven([6, 6, 7, 2, 7, 7]) returns tuple (7, 3)

# Your code here

assert count_six_seven([6]) == (6, 1)
assert count_six_seven([6, 6, 7]) == (6, 2)
assert count_six_seven([7]) == (7, 1)
assert count_six_seven([6 if i < 5 else 7 for i in range(100)]) == (7, 95)

Problem 4

Write a function char_counter that takes as argument a string and returns a tuple. The first element of the tuple should be the most common character in the string; the second element of the tuple should be how many times that character appears. Assume that there is a single most common character.

# Your code here

assert char_counter("hello") == ('l', 2)
assert char_counter("AABA") == ('A', 3)
assert char_counter("char count") == ('c', 2)
assert char_counter("A B C D") == (' ', 3)

Problem 5

Write a function find_run that takes as argument a list of integers. Your function should find a sequential run of integers within the list, and return a tuple with two elements: the first and last elements of the run. Assume there is exactly one run in the list.

A sequential run is a sequence of integers where each is one greater than the previous.

find_run([1, 2, 3, 5]) returns tuple (1, 3)
find_run([0, 4, 5, 6, 7, 8, 1]) returns tuple (4, 8)
find_run([2, 0, 1, 3, 5]) returns tuple (0, 1)

Note: This is a hard problem.

# Your code here

assert find_run([1, 1, 1, 2, 3, 4, 6]) == (1, 4)
assert find_run([1, 1, 2, 2, 7, 4, 6]) == (1, 2)
assert find_run([0, 0, 3, 4, 5, 0, 0, 0]) == (3, 5)
assert find_run([5, 4, 13, 14, 15, 16, 5]) == (13, 16)

Back to Week 10 Notes