Compress a route by removing collinear points

route_compress.py

def compress_route(route):
  compressed = []
  for point in route:
    compressed.append(point)
    if len(compressed) >= 3 and is_collinear(*compressed[-3:]):
      del compressed[-2]

  return compressed

def is_collinear(a, b, c):
  return abs((a[0]*(b[1]-c[1])+b[0]*(c[1]-a[1])+c[0]*(a[1]-b[1]))/2) == 0

assert is_collinear([0, 5], [5, 5], [10, 5])
assert not is_collinear([0, 5], [5, 10], [10, 5])

assert [[0, 1], [2, 1], [2, 4], [5, 7], [9, 7]] == compress_route([
  [0, 1],
  [1, 1],
  [2, 1],
  [2, 2],
  [2, 3],
  [2, 4],
  [3, 5],
  [4, 6],
  [5, 7],
  [7, 7],
  [8, 7],
  [9, 7],
])