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"""

A 2-dimensional vector class

>>> v1 = Vector2d(3, 4)

>>> print(v1.x, v1.y)

3.0 4.0

>>> x, y = v1

>>> x, y

(3.0, 4.0)

>>> v1

Vector2d(3.0, 4.0)

>>> v1_clone = eval(repr(v1))

>>> v1 == v1_clone

True

>>> print(v1)

(3.0, 4.0)

>>> octets = bytes(v1)

>>> octets

b'd\\x00\\x00\\x00\\x00\\x00\\x00\\x08@\\x00\\x00\\x00\\x00\\x00\\x00\\x10@'

>>> abs(v1)

5.0

>>> bool(v1), bool(Vector2d(0, 0))

(True, False)

Test of ``.frombytes()`` class method:

>>> v1_clone = Vector2d.frombytes(bytes(v1))

>>> v1_clone

Vector2d(3.0, 4.0)

>>> v1 == v1_clone

True

"""

from array import array

import math

class Vector2d:

typecode = 'd'

def __init__(self, x, y):

self.x = float(x)

self.y = float(y)

def __iter__(self):

return (i for i in (self.x, self.y))

def __repr__(self):

class_name = type(self).__name__

return '{}({!r}, {!r})'.format(class_name, *self)

def __str__(self):

return str(tuple(self))

def __bytes__(self):

return (bytes([ord(self.typecode)]) +

bytes(array(self.typecode, self)))

def __eq__(self, other):

return tuple(self) == tuple(other)

def __abs__(self):

return math.hypot(self.x, self.y)

def __bool__(self):

return bool(abs(self))

# BEGIN VECTOR2D_V1

@classmethod # <1>

def frombytes(cls, octets): # <2>

typecode = chr(octets[0]) # <3>

memv = memoryview(octets[1:]).cast(typecode) # <4>

return cls(*memv) # <5>

# END VECTOR2D_V1