124 lines
2.6 KiB
Python
124 lines
2.6 KiB
Python
"""
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A 2-dimensional vector class
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>>> v1 = Vector(3, 4)
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>>> x, y = v1 #<1>
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>>> x, y
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(3.0, 4.0)
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>>> v1 #<2>
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Vector(3.0, 4.0)
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>>> v1_clone = eval(repr(v1)) #<3>
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>>> v1 == v1_clone
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True
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>>> print(v1) #<4>
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(3.0, 4.0)
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>>> octets = bytes(v1) #<5>
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>>> octets
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b'\\x00\\x00\\x00\\x00\\x00\\x00\\x08@\\x00\\x00\\x00\\x00\\x00\\x00\\x10@'
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>>> abs(v1) #<6>
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5.0
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>>> bool(v1), bool(Vector(0, 0)) #<7>
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(True, False)
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Test of .frombytes() class method:
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>>> v1_clone = Vector.frombytes(bytes(v1))
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>>> v1_clone
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Vector(3.0, 4.0)
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>>> v1 == v1_clone
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True
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# BEGIN VECTOR_V3_DEMO
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Test 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
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# END VECTOR_V3_HASH_DEMO
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# BEGIN VECTOR_V3_HASH_DEMO
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>>> v1 = Vector(3, 4)
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>>> v2 = Vector(3.1, 4.2)
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>>> hash(v1), hash(v2)
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(7, 384307168202284039)
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>>> set([v1, v2])
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{Vector(3.1, 4.2), Vector(3.0, 4.0)}
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# END VECTOR_V3_DEMO
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"""
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from array import array
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import math
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# BEGIN VECTOR_V3
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class Vector:
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typecode = 'd'
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def __init__(self, x, y):
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self.__x = float(x) # <1>
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self.__y = float(y)
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@property # <2>
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def x(self): # <3>
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return self.__x # <4>
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@property # <5>
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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)) # <6>
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# remaining methods follow (omitted in book listing)
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# END VECTOR_V3
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def __repr__(self):
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return 'Vector({!r}, {!r})'.format(*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(array(Vector.typecode, self))
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def __eq__(self, other):
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return tuple(self) == tuple(other)
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# BEGIN VECTOR_V3_HASH
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def __hash__(self):
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return hash(self.x) ^ hash(self.y)
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# END VECTOR_V3_HASH
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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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arr = array(Vector.typecode)
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arr.frombytes(octets)
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return cls(*arr)
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