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31 lines
883 B
Python
31 lines
883 B
Python
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def area_of_polygon(xs: list[float], ys: list[float]) -> float:
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"""
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Compute the area of a polygon. The polygon has to be planar and simple
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(not self-intersecting). The vertices have to be ordered in the
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counter-clockwise direction.
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https://en.wikipedia.org/wiki/Shoelace_formula
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Args:
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xs: list of x coordinates of the polygon vertices in counter-clockwise order
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ys: list of y coordinates of the polygon vertices in counter-clockwise order
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Returns:
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area of the polygon
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>>> from math import isclose
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>>> xs = [1, 3, 7, 4, 8]
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>>> ys = [6, 1, 2, 4, 5]
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>>> isclose(area_of_polygon(xs, ys), 16.5)
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True
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"""
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return 0.5 * sum(
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(ys[i] + ys[(i + 1) % len(ys)]) * (xs[i] - xs[(i + 1) % len(xs)])
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for i in range(len(xs))
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)
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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