#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
swinging_door
=============
Implementation of the SwingingDoor algorithm in Python.
"""
from typing import TYPE_CHECKING
if TYPE_CHECKING: # pragma: no cover
from typing import Generator, List, Tuple
Point = Tuple[float, float]
__author__ = "Aleksandr F. Mikhaylov (ChelAxe)" # type: str
__version__ = "1.0.1" # type: str
__license__ = "MIT" # type: str
[docs]
def swinging_door( # pylint: disable=too-many-locals
data, # type: List[Point]
deviation=0.1, # type: float
mode=False, # type: bool
step=10, # type: int
):
# type: (...) -> Generator[Point, None, None]
"""
Implementation of the SwingingDoor algorithm.
:param List[Point] data: data;
:param float deviation: compression deflection;
:param bool mode: use a modified algorithm;
:param int step: step for the modified algorithm.
:rtype: Generator[Point, None, None]
:return: Compressed data.
>>> list(swinging_door([
... (0., 5.0), (1., 5.5), (2., 4.2),
... (3., 5.8), (4., 5.2), (5., 6.8),
... ], deviation=1.))
[(0.0, 5.0), (4.5, 5.5), (5.0, 6.8)]
>>> list(swinging_door([
... (0., 5.0), (1., 5.5), (2., 4.2),
... (3., 5.8), (4., 5.2), (5., 2.8),
... ], deviation=1.))
[(0.0, 5.0), (4.5, 3.5), (5.0, 2.8)]
>>> list(swinging_door([
... (0., 5.0), (1., 5.5), (2., 4.2),
... (3., 5.8), (4., 5.2), (5., 6.8),
... ], deviation=1., mode=True))
[(0.0, 5.0), (4.0, 5.2), (5.0, 6.8)]
>>> list(swinging_door([
... (0., 5.0), (1., 5.5), (2., 4.2),
... (3., 5.8), (4., 5.2), (5., 6.8),
... ], deviation=1., mode=True, step=2))
[(0.0, 5.0), (2.0, 4.2), (5.0, 6.8)]
"""
current_step = 0 # type: int
upper_pivot = lower_pivot = current = (0.0, 0.0) # type: Point
sloping_upper_max = sloping_lower_min = 0.0 # type: float
for i, item in enumerate(data):
if not i:
entrance = current = item
upper_pivot = (
entrance[0],
entrance[1] + deviation,
)
lower_pivot = (
entrance[0],
entrance[1] - deviation,
)
yield entrance
current_step = 0
continue
past, current = current, item
sloping_upper = (current[1] - upper_pivot[1]) / (
current[0] - upper_pivot[0]
) # type: float
sloping_lower = (current[1] - lower_pivot[1]) / (
current[0] - lower_pivot[0]
) # type: float
if not sloping_upper_max and not sloping_lower_min:
sloping_upper_max = sloping_upper
sloping_lower_min = sloping_lower
current_step += 1
continue
if sloping_upper > sloping_upper_max:
sloping_upper_max = sloping_upper
if sloping_upper_max > sloping_lower_min:
entrance = (
past
if mode
else (
(past[0] + current[0]) / 2,
(past[1] + current[1]) / 2 - (deviation / 2),
)
)
yield entrance
current_step = 0
upper_pivot = entrance[0], entrance[1] + deviation
lower_pivot = entrance[0], entrance[1] - deviation
sloping_upper_max = (current[1] - upper_pivot[1]) / (
current[0] - upper_pivot[0]
)
sloping_lower_min = (current[1] - lower_pivot[1]) / (
current[0] - lower_pivot[0]
)
elif sloping_lower < sloping_lower_min:
sloping_lower_min = sloping_lower
if sloping_upper_max > sloping_lower_min:
entrance = (
past
if mode
else (
(past[0] + current[0]) / 2,
(past[1] + current[1]) / 2 - (deviation / 2),
)
)
yield entrance
current_step = 0
upper_pivot = entrance[0], entrance[1] + deviation
lower_pivot = entrance[0], entrance[1] - deviation
sloping_upper_max = (current[1] - upper_pivot[1]) / (
current[0] - upper_pivot[0]
)
sloping_lower_min = (current[1] - lower_pivot[1]) / (
current[0] - lower_pivot[0]
)
if mode and current_step == step:
entrance = past
yield entrance
current_step = 0
upper_pivot = entrance[0], entrance[1] + deviation
lower_pivot = entrance[0], entrance[1] - deviation
sloping_upper_max = (current[1] - upper_pivot[1]) / (
current[0] - upper_pivot[0]
)
sloping_lower_min = (current[1] - lower_pivot[1]) / (
current[0] - lower_pivot[0]
)
else:
current_step += 1
yield current
