77 lines
1.6 KiB
Python
77 lines
1.6 KiB
Python
"""
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A 2-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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"""
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from array import array
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import math
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class Vector2d:
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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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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 __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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# tag::VECTOR2D_V1[]
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@classmethod # <1>
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def frombytes(cls, octets): # <2>
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typecode = chr(octets[0]) # <3>
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memv = memoryview(octets[1:]).cast(typecode) # <4>
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return cls(*memv) # <5>
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# end::VECTOR2D_V1[]
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