monotone.py

"""
Story

Peter lives on a hill, and he always moans about the way to his home.
"It's always just up. I never get a rest".
But you're pretty sure that at least at one point
Peter's altitude doesn't rise, but fall.
To get him, you use a nefarious plan:
  you attach an altimeter to his backpack
  and you read the data from his way back at the next day.

Task

You're given a list of compareable elements:

heights = [Integers or Floats]
Your job is to check whether for any x all successors are greater or equal to x.

is_monotone([1,2,3]) == True
is_monotone([1,1,2]) == True
is_monotone([1])     == True
is_monotone([3,2,1]) == False
is_monotone([3,2,2]) == False
If the list is empty, Peter has probably removed your altimeter,
so we cannot prove him wrong and he's still right:

is_monotone([])     == True
Such a sequence is also called monotone or monotonic sequence, hence the name isMonotone.
"""

def is_monotone(heights):
    """
    if len(heights) == 0 or len(heights) == 1:
        return True

    cur_height = heights[0]
    for height in heights:
        if cur_height > height:
            return False

        cur_height = height

    return True
    """
    return sorted(heights) == heights


from unittest import TestCase

class TestMonotone(TestCase):
    def test_monotone(self):
        self.assertTrue(is_monotone(range(1, 11)), 'Should work on increasing lists')
        self.assertTrue(is_monotone([5,5,5,5,5,5,5]), 'Should work on constant lists')
        self.assertTrue(is_monotone([]), 'Should work on empty list')
        self.assertTrue(is_monotone([1]), 'Should work on size 1 list')

        self.assertTrue(not is_monotone(range(5, 0, -1)), 'Should return false on a decreasing list')
        self.assertTrue(not is_monotone(range(5, -40, -1)), 'Should return false on a decreasing list')