154 lines
3.2 KiB
Python
154 lines
3.2 KiB
Python
"""
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A two-dimensional vector class
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>>> v1 = Vector2d(3, 4)
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>>> print(v1.x, v1.y)
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3.0 4.0
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>>> x, y = v1
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>>> x, y
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(3.0, 4.0)
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>>> v1
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Vector2d(3.0, 4.0)
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>>> v1_clone = eval(repr(v1))
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>>> v1 == v1_clone
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True
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>>> print(v1)
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(3.0, 4.0)
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>>> octets = bytes(v1)
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>>> octets
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b'd\\x00\\x00\\x00\\x00\\x00\\x00\\x08@\\x00\\x00\\x00\\x00\\x00\\x00\\x10@'
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>>> abs(v1)
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5.0
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>>> bool(v1), bool(Vector2d(0, 0))
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(True, False)
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Test of ``.frombytes()`` class method:
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>>> v1_clone = Vector2d.frombytes(bytes(v1))
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>>> v1_clone
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Vector2d(3.0, 4.0)
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>>> v1 == v1_clone
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True
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Tests of ``format()`` with Cartesian coordinates:
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>>> format(v1)
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'(3.0, 4.0)'
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>>> format(v1, '.2f')
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'(3.00, 4.00)'
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>>> format(v1, '.3e')
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'(3.000e+00, 4.000e+00)'
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Tests of the ``angle`` method::
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>>> Vector2d(0, 0).angle()
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0.0
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>>> Vector2d(1, 0).angle()
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0.0
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>>> epsilon = 10**-8
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>>> abs(Vector2d(0, 1).angle() - math.pi/2) < epsilon
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True
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>>> abs(Vector2d(1, 1).angle() - math.pi/4) < epsilon
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True
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Tests of ``format()`` with polar coordinates:
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>>> format(Vector2d(1, 1), 'p') # doctest:+ELLIPSIS
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'<1.414213..., 0.785398...>'
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>>> format(Vector2d(1, 1), '.3ep')
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'<1.414e+00, 7.854e-01>'
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>>> format(Vector2d(1, 1), '0.5fp')
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'<1.41421, 0.78540>'
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Tests of `x` and `y` read-only properties:
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>>> v1.x, v1.y
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(3.0, 4.0)
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>>> v1.x = 123
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Traceback (most recent call last):
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...
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AttributeError: can't set attribute 'x'
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Tests of hashing:
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>>> v1 = Vector2d(3, 4)
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>>> v2 = Vector2d(3.1, 4.2)
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>>> hash(v1), hash(v2)
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(7, 384307168202284039)
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>>> len({v1, v2})
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2
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"""
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from array import array
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import math
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class Vector2d:
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__match_args__ = ('x', 'y')
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typecode = 'd'
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def __init__(self, x, y):
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self.__x = float(x)
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self.__y = float(y)
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@property
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def x(self):
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return self.__x
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@property
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def y(self):
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return self.__y
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def __iter__(self):
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return (i for i in (self.x, self.y))
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def __repr__(self):
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class_name = type(self).__name__
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return '{}({!r}, {!r})'.format(class_name, *self)
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def __str__(self):
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return str(tuple(self))
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def __bytes__(self):
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return (bytes([ord(self.typecode)]) +
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bytes(array(self.typecode, self)))
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def __eq__(self, other):
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return tuple(self) == tuple(other)
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def __hash__(self):
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return hash(self.x) ^ hash(self.y)
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def __abs__(self):
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return math.hypot(self.x, self.y)
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def __bool__(self):
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return bool(abs(self))
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def angle(self):
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return math.atan2(self.y, self.x)
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def __format__(self, fmt_spec=''):
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if fmt_spec.endswith('p'):
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fmt_spec = fmt_spec[:-1]
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coords = (abs(self), self.angle())
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outer_fmt = '<{}, {}>'
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else:
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coords = self
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outer_fmt = '({}, {})'
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components = (format(c, fmt_spec) for c in coords)
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return outer_fmt.format(*components)
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@classmethod
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def frombytes(cls, octets):
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typecode = chr(octets[0])
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memv = memoryview(octets[1:]).cast(typecode)
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return cls(*memv)
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