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"""
PolymorphicRelatedQuerySet which allows select_related()  to return polymorphic child models instead of base model
Based on code by AndySun25 at: https://gist.github.com/AndySun25/157da4195c139a38ec3d609a277773cb
To address issue: https://github.com/django-polymorphic/django-polymorphic/issues/244
Added support for Polymorphic Proxy Models
"""

import functools
from django.db import models
from django.db.models.constants import LOOKUP_SEP

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from functools import total_ordering
from math import sqrt

@total_ordering
class Vector(object):
    """
    Simple class to represent a 2D vector with X and Y components.
    Could extend with more useful methods etc
    """
    def __init__(self, x, y):

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import numpy as np
import pandas as pd
from pandas.core.dtypes.dtypes import PandasExtensionDtype
from pandas.api.extensions import ExtensionArray, ExtensionScalarOpsMixin, register_extension_dtype

@register_extension_dtype
class VectorDtype(PandasExtensionDtype):
    """
    Class to describe the custom Vector data type
    """

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class VectorArray(ExtensionScalarOpsMixin, ExtensionArray):
    """
    Custom Extension Array type for an array of Vectors
    Needs to define:
    - Associated Dtype it is used with
    - How to construct array from sequence of scalars
    - How data is stored and accessed
    - Any custom array methods
    """