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- # -*- coding: utf-8 -*-
- import math
- from .util import SQRT2
- def null(dx, dy):
- """
- special heuristic for Dijkstra
- return 0, so node.h will always be calculated as 0,
- distance cost (node.f) is calculated only from
- start to current point (node.g)
- """
- return 0
- def manhatten(dx, dy):
- """manhatten heuristics"""
- return dx + dy
- def euclidean(dx, dy):
- """euclidean distance heuristics"""
- return math.sqrt(dx * dx + dy * dy)
- def chebyshev(dx, dy):
- """ Chebyshev distance. """
- return max(dx, dy)
- def octile(dx, dy):
- f = SQRT2 - 1
- if dx < dy:
- return f * dx + dy
- else:
- return f * dy + dx
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