import numpy as np
from struct import pack, unpack_from
NO_DEFAULT = object()
class SparseVector:
def __init__(self, value, dimensions=NO_DEFAULT, /):
if value.__class__.__module__.startswith('scipy.sparse.'):
if dimensions is not NO_DEFAULT:
raise ValueError('extra argument')
self._from_sparse(value)
elif isinstance(value, dict):
if dimensions is NO_DEFAULT:
raise ValueError('missing dimensions')
self._from_dict(value, dimensions)
else:
if dimensions is not NO_DEFAULT:
raise ValueError('extra argument')
self._from_dense(value)
def __repr__(self):
elements = dict(zip(self._indices, self._values))
return f'SparseVector({elements}, {self._dim})'
def __eq__(self, other):
if isinstance(other, self.__class__):
return self.dimensions() == other.dimensions() and self.indices() == other.indices() and self.values() == other.values()
return False
def dimensions(self):
return self._dim
def indices(self):
return self._indices
def values(self):
return self._values
def to_coo(self):
from scipy.sparse import coo_array
coords = ([0] * len(self._indices), self._indices)
return coo_array((self._values, coords), shape=(1, self._dim))
def to_list(self):
vec = [0.0] * self._dim
for i, v in zip(self._indices, self._values):
vec[i] = v
return vec
def to_numpy(self):
vec = np.repeat(0.0, self._dim).astype(np.float32)
for i, v in zip(self._indices, self._values):
vec[i] = v
return vec
def to_text(self):
return '{' + ','.join([f'{int(i) + 1}:{float(v)}' for i, v in zip(self._indices, self._values)]) + '}/' + str(int(self._dim))
def to_binary(self):
nnz = len(self._indices)
return pack(f'>iii{nnz}i{nnz}f', self._dim, nnz, 0, *self._indices, *self._values)
def _from_dict(self, d, dim):
elements = [(i, v) for i, v in d.items() if v != 0]
elements.sort()
self._dim = int(dim)
self._indices = [int(v[0]) for v in elements]
self._values = [float(v[1]) for v in elements]
def _from_sparse(self, value):
value = value.tocoo()
if value.ndim == 1:
self._dim = value.shape[0]
elif value.ndim == 2 and value.shape[0] == 1:
self._dim = value.shape[1]
else:
raise ValueError('expected ndim to be 1')
if hasattr(value, 'coords'):
# scipy 1.13+
self._indices = value.coords[0].tolist()
else:
self._indices = value.col.tolist()
self._values = value.data.tolist()
def _from_dense(self, value):
self._dim = len(value)
self._indices = [i for i, v in enumerate(value) if v != 0]
self._values = [float(value[i]) for i in self._indices]
@classmethod
def from_text(cls, value):
elements, dim = value.split('/', 2)
indices = []
values = []
# split on empty string returns single element list
if len(elements) > 2:
for e in elements[1:-1].split(','):
i, v = e.split(':', 2)
indices.append(int(i) - 1)
values.append(float(v))
return cls._from_parts(int(dim), indices, values)
@classmethod
def from_binary(cls, value):
dim, nnz, unused = unpack_from('>iii', value)
indices = unpack_from(f'>{nnz}i', value, 12)
values = unpack_from(f'>{nnz}f', value, 12 + nnz * 4)
return cls._from_parts(int(dim), list(indices), list(values))
@classmethod
def _from_parts(cls, dim, indices, values):
vec = cls.__new__(cls)
vec._dim = dim
vec._indices = indices
vec._values = values
return vec
@classmethod
def _to_db(cls, value, dim=None):
if value is None:
return value
if not isinstance(value, cls):
value = cls(value)
if dim is not None and value.dimensions() != dim:
raise ValueError('expected %d dimensions, not %d' % (dim, value.dimensions()))
return value.to_text()
@classmethod
def _to_db_binary(cls, value):
if value is None:
return value
if not isinstance(value, cls):
value = cls(value)
return value.to_binary()
@classmethod
def _from_db(cls, value):
if value is None or isinstance(value, cls):
return value
return cls.from_text(value)
@classmethod
def _from_db_binary(cls, value):
if value is None or isinstance(value, cls):
return value
return cls.from_binary(value)