def sample(self, bqm, *args, **kwargs):
msg = ("PolySampler.sample is deprecated and will be removed in dimod "
"0.9.0. In the future, when using PolySamplers, you should use "
".sample_poly")
warnings.warn(msg, DeprecationWarning)
poly = BinaryPolynomial(bqm.quadratic)
poly.update(((v, ), bias) for v, bias in bqm.linear.items())
return self.sample_poly(poly, *args, **kwargs)
def poly_energy(sample_like, poly):
"""Calculates energy of a sample from a higher order polynomial.
Args:
sample (samples_like):
A raw sample. `samples_like` is an extension of NumPy's
array_like structure. See :func:`.as_samples`.
poly (dict):
Polynomial as a dict of form {term: bias, ...}, where `term` is a
tuple of variables and `bias` the associated bias.
Returns:
float: The energy of the sample.
"""
return BinaryPolynomial(poly, 'SPIN').energy(sample_like)
def poly_energies(samples_like, poly):
"""Calculates energy of samples from a higher order polynomial.
Args:
sample (samples_like):
A collection of raw samples. `samples_like` is an extension of
NumPy's array_like structure. See :func:`.as_samples`.
poly (dict):
Polynomial as a dict of form {term: bias, ...}, where `term` is a
tuple of variables and `bias` the associated bias. Variable
labeling/indexing of terms in poly dict must match that of the
sample(s).
Returns:
list/:obj:`numpy.ndarray`: The energy of the sample(s).
"""
return BinaryPolynomial(poly, 'SPIN').energies(samples_like)
def fix_variables(poly, fixed_variables):
if () in poly.keys():
offset = poly[()]
else:
offset = 0.0
poly_copy = defaultdict(float)
for k, v in poly.items():
k = set(k)
for var, value in fixed_variables.items():
if var in k:
k -= {var}
v *= value
k = frozenset(k)
if len(k) > 0:
poly_copy[k] += v
else:
offset += v
poly_copy[()] = offset
return BinaryPolynomial(poly_copy, poly.vartype)
def poly_energy(sample_like, poly):
"""Calculates energy of a sample from a higher order polynomial.
Args:
sample (samples_like):
A raw sample. `samples_like` is an extension of NumPy's
array_like structure. See :func:`.as_samples`.
poly (dict):
Polynomial as a dict of form {term: bias, ...}, where `term` is a
tuple of variables and `bias` the associated bias.
Returns:
float: The energy of the sample.
"""
msg = ("poly_energy is deprecated and will be removed in dimod 0.9.0."
"In the future, use BinaryPolynomial.energy")
warnings.warn(msg, DeprecationWarning)
# dev note the vartype is not used in the energy calculation and this will
# be deprecated in the future
return BinaryPolynomial(poly, 'SPIN').energy(sample_like)
def poly_energies(samples_like, poly):
"""Calculates energy of samples from a higher order polynomial.
Args:
sample (samples_like):
A collection of raw samples. `samples_like` is an extension of
NumPy's array_like structure. See :func:`.as_samples`.
poly (dict):
Polynomial as a dict of form {term: bias, ...}, where `term` is a
tuple of variables and `bias` the associated bias. Variable
labeling/indexing of terms in poly dict must match that of the
sample(s).
Returns:
list/:obj:`numpy.ndarray`: The energy of the sample(s).
"""
msg = ("poly_energies is deprecated and will be removed in dimod 0.9.0."
"In the future, use BinaryPolynomial.energies")
warnings.warn(msg, DeprecationWarning)
# dev note the vartype is not used in the energy calculation and this will
# be deprecated in the future
return BinaryPolynomial(poly, 'SPIN').energies(samples_like)
def _init_binary_polynomial(poly, vartype):
if not (isinstance(poly, BinaryPolynomial) and
(vartype in (poly.vartype, None))):
poly = BinaryPolynomial(poly, vartype=vartype)
return poly
def make_quadratic(poly, strength, vartype=None, bqm=None):
"""Create a binary quadratic model from a higher order polynomial.
Args:
poly (dict):
Polynomial as a dict of form {term: bias, ...}, where `term` is a tuple of
variables and `bias` the associated bias.
strength (float):
The energy penalty for violating the prodcut constraint.
Insufficient strength can result in the binary quadratic model not
having the same minimizations as the polynomial.
vartype (:class:`.Vartype`/str/set, optional):
Variable type for the binary quadratic model. Accepted input values:
* :class:`.Vartype.SPIN`, ``'SPIN'``, ``{-1, 1}``
* :class:`.Vartype.BINARY`, ``'BINARY'``, ``{0, 1}``
If `bqm` is provided, `vartype` is not required.
bqm (:class:`.BinaryQuadraticModel`, optional):
The terms of the reduced polynomial are added to this binary quadratic model.
If not provided, a new binary quadratic model is created.
Returns:
:class:`.BinaryQuadraticModel`
Examples:
>>> poly = {(0,): -1, (1,): 1, (2,): 1.5, (0, 1): -1, (0, 1, 2): -2}
>>> bqm = dimod.make_quadratic(poly, 5.0, dimod.SPIN)
"""
if vartype is None:
if bqm is None:
raise ValueError("one of vartype or bqm must be provided")
else:
vartype = bqm.vartype
else:
vartype = as_vartype(vartype) # handle other vartype inputs
if bqm is None:
bqm = BinaryQuadraticModel.empty(vartype)
else:
bqm = bqm.change_vartype(vartype, inplace=False)
bqm.info['reduction'] = {}
# we want to be able to mutate the polynomial so copy. We treat this as a
# dict but by using BinaryPolynomial we also get automatic handling of
# square terms
poly = BinaryPolynomial(poly, vartype=bqm.vartype)
variables = set().union(*poly)
while any(len(term) > 2 for term in poly):
# determine which pair of variables appear most often
paircounter = Counter()
for term in poly:
if len(term) <= 2:
# we could leave these in but it can lead to cases like
# {'ab': -1, 'cdef': 1} where ab keeps being chosen for
# elimination. So we just ignore all the pairs
continue
for u, v in itertools.combinations(term, 2):
pair = frozenset((u, v)) # so order invarient
paircounter[pair] += 1
pair, __ = paircounter.most_common(1)[0]
u, v = pair
# make a new product variable p == u*v and replace all (u, v) with p
p = _new_product(variables, u, v)
terms = [term for term in poly if u in term and v in term]
for term in terms:
new = tuple(w for w in term if w != u and w != v) + (p, )
poly[new] = poly.pop(term)
# add a constraint enforcing the relationship between p == u*v
if vartype is Vartype.BINARY:
constraint = _binary_product([u, v, p])
bqm.info['reduction'][(u, v)] = {'product': p}
elif vartype is Vartype.SPIN:
aux = _new_aux(variables, u, v) # need an aux in SPIN-space
constraint = _spin_product([u, v, p, aux])
bqm.info['reduction'][(u, v)] = {'product': p, 'auxiliary': aux}
else:
raise RuntimeError("unknown vartype: {!r}".format(vartype))
# scale constraint and update the polynomial with it
constraint.scale(strength)
for v, bias in constraint.linear.items():
try:
poly[v, ] += bias
except KeyError:
poly[v, ] = bias
for uv, bias in constraint.quadratic.items():
try:
poly[uv] += bias
except KeyError:
poly[uv] = bias
try:
poly[()] += constraint.offset
except KeyError:
poly[()] = constraint.offset
# convert poly to a bqm (it already is one)
for term, bias in poly.items():
if len(term) == 2:
u, v = term
bqm.add_interaction(u, v, bias)
elif len(term) == 1:
v, = term
bqm.add_variable(v, bias)
elif len(term) == 0:
bqm.add_offset(bias)
else:
# still has higher order terms, this shouldn't happen
msg = ('Internal error: not all higher-order terms were reduced. '
'Please file a bug report.')
raise RuntimeError(msg)
return bqm