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from django.db.models import FloatField, Func, Value
from ..utils import Vector, HalfVector, SparseVector
class DistanceBase(Func):
output_field = FloatField()
def __init__(self, expression, vector, **extra):
if not hasattr(vector, 'resolve_expression'):
if isinstance(vector, HalfVector):
vector = Value(HalfVector._to_db(vector))
elif isinstance(vector, SparseVector):
vector = Value(SparseVector._to_db(vector))
else:
vector = Value(Vector._to_db(vector))
super().__init__(expression, vector, **extra)
class BitDistanceBase(Func):
output_field = FloatField()
def __init__(self, expression, vector, **extra):
if not hasattr(vector, 'resolve_expression'):
vector = Value(vector)
super().__init__(expression, vector, **extra)
class L2Distance(DistanceBase):
function = ''
arg_joiner = ' <-> '
class MaxInnerProduct(DistanceBase):
function = ''
arg_joiner = ' <#> '
class CosineDistance(DistanceBase):
function = ''
arg_joiner = ' <=> '
class L1Distance(DistanceBase):
function = ''
arg_joiner = ' <+> '
class HammingDistance(BitDistanceBase):
function = ''
arg_joiner = ' <~> '
class JaccardDistance(BitDistanceBase):
function = ''
arg_joiner = ' <%%> '
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