167 lines
3.5 KiB
Python
167 lines
3.5 KiB
Python
"""
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A multi-dimensional ``Vector`` class, take 2
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A ``Vector`` is built from an iterable of numbers::
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>>> Vector([3.1, 4.2])
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Vector([3.1, 4.2])
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>>> Vector((3, 4, 5))
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Vector([3.0, 4.0, 5.0])
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>>> Vector(range(10))
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Vector([0.0, 1.0, 2.0, 3.0, 4.0, ...])
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Tests with 2-dimensions (same results as ``vector2d_v1.py``)::
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>>> v1 = Vector([3, 4])
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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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Vector([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(Vector([0, 0]))
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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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Tests with 3-dimensions::
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>>> v1 = Vector([3, 4, 5])
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>>> x, y, z = v1
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>>> x, y, z
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(3.0, 4.0, 5.0)
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>>> v1
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Vector([3.0, 4.0, 5.0])
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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, 5.0)
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>>> abs(v1) # doctest:+ELLIPSIS
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7.071067811...
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>>> bool(v1), bool(Vector([0, 0, 0]))
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(True, False)
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Tests with many dimensions::
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>>> v7 = Vector(range(7))
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>>> v7
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Vector([0.0, 1.0, 2.0, 3.0, 4.0, ...])
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>>> abs(v7) # doctest:+ELLIPSIS
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9.53939201...
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Test of ``.__bytes__`` and ``.frombytes()`` methods::
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>>> v1 = Vector([3, 4, 5])
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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, 5.0])
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>>> v1 == v1_clone
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True
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Tests of sequence behavior::
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>>> v1 = Vector([3, 4, 5])
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>>> len(v1)
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3
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>>> v1[0], v1[len(v1)-1], v1[-1]
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(3.0, 5.0, 5.0)
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Test of slicing::
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# BEGIN VECTOR_V2_DEMO
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>>> v7 = Vector(range(7))
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>>> v7[-1] # <1>
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6.0
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>>> v7[1:4] # <2>
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Vector([1.0, 2.0, 3.0])
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>>> v7[-1:] # <3>
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Vector([6.0])
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>>> v7[1,2] # <4>
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Traceback (most recent call last):
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...
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TypeError: Vector indices must be integers
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# END VECTOR_V2_DEMO
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"""
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from array import array
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import reprlib
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import math
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class Vector:
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typecode = 'd'
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def __init__(self, components):
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self._components = array(self.typecode, components)
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def __iter__(self):
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return iter(self._components)
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def __repr__(self):
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components = reprlib.repr(self._components)
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components = components[components.find('['):-1]
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return 'Vector({})'.format(components)
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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(self._components))
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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.sqrt(sum(x * x for x in self))
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def __bool__(self):
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return bool(abs(self))
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# BEGIN VECTOR_V2
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def __len__(self):
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return len(self._components)
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def __getitem__(self, index):
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cls = type(self) # <1>
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if isinstance(index, slice):
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return cls(self._components[index]) # <2>
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elif isinstance(index, int):
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return self._components[index] # <3>
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else:
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msg = '{cls.__name__} indices must be integers'
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raise TypeError(msg.format(cls=cls)) # <4>
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# END VECTOR_V2
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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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