def test_pstring_collection_len():
x = PauliString(spec="X", support=(0,))
y = PauliString(spec="Y", support=(1,))
z = PauliString(spec="Z", support=(2,))
assert len(PauliStringCollection(x, y, z)) == 3
assert len(PauliStringCollection(x, x, x)) == 3
assert len(PauliStringCollection(x, y)) == 2
assert len(PauliStringCollection(x)) == 1
assert len(PauliStringCollection()) == 0
def test_pstringcollection_expectation_from_measurements_qubit_indices():
measurements = MeasurementResult([[0, 0], [0, 0], [0, 1], [0, 1]],
qubit_indices=(1, 5))
pset = PauliStringCollection(
PauliString(spec="Z", coeff=-2.0, support=(1, )))
assert np.isclose(pset._expectation_from_measurements(measurements), -2.0)
pset = PauliStringCollection(
PauliString(spec="Z", coeff=-2.0, support=(5, )))
assert np.isclose(pset._expectation_from_measurements(measurements), 0.0)
def test_pstringcollection_expectation_from_measurements():
measurements = MeasurementResult([[0, 0], [0, 0], [0, 1], [0, 1]])
pset = PauliStringCollection(PauliString(spec="ZI", coeff=-2.0),
PauliString(spec="IZ", coeff=5.0))
assert np.isclose(pset._expectation_from_measurements(measurements), -2.0)
measurements = MeasurementResult([[1, 0], [1, 0], [0, 1], [0, 1]])
pset = PauliStringCollection(PauliString(spec="ZI", coeff=-2.0),
PauliString(spec="IZ", coeff=5.0))
assert np.isclose(pset._expectation_from_measurements(measurements), 0.0)
def test_observable_from_pauli_string_collections():
z = PauliString("Z")
zz = PauliString("ZZ")
pcol1 = PauliStringCollection(z, zz)
x = PauliString("X")
xx = PauliString("XX")
pcol2 = PauliStringCollection(x, xx)
obs = Observable.from_pauli_string_collections(pcol1, pcol2)
assert obs.ngroups == 2
assert obs.groups[0] == pcol1
assert obs.groups[1] == pcol2
assert obs.nterms == 4
def test_observable_partition_single_qubit_paulis():
x = PauliString(spec="X")
y = PauliString(spec="Y")
z = PauliString(spec="Z")
obs = Observable(x, y, z)
assert obs.nterms == 3
obs.partition(seed=2)
expected_groups = [
PauliStringCollection(x),
PauliStringCollection(y),
PauliStringCollection(z),
]
assert obs.groups == expected_groups
def test_pstring_collection_empty():
pauli_collection = PauliStringCollection()
assert pauli_collection.elements == []
assert pauli_collection.elements_by_weight == {}
assert pauli_collection.min_weight() == 0
assert pauli_collection.support() == set()
assert len(pauli_collection) == 0
def test_pstring_collection_eq():
x = PauliString(spec="X")
z = PauliString(spec="IZ")
xz = PauliString(spec="XZ")
xzz = PauliString(spec="IIIXZZ")
assert PauliStringCollection(x, xzz) == PauliStringCollection(xzz, x)
assert PauliStringCollection(x, z) != PauliStringCollection(x, xz)
assert PauliStringCollection(x, z, xz) == PauliStringCollection(z, xz, x)
assert PauliStringCollection() == PauliStringCollection()
def test_pstring_collection_str():
x = PauliString(spec="X")
iz = PauliString(spec="IZ")
pcol = PauliStringCollection(x, iz)
assert str(pcol) == "X(0) + Z(1)"
xz = PauliString(spec="XZ", coeff=-2.4)
pcol.add(xz)
assert str(pcol) == "X(0) + Z(1) + (-2.4+0j)*X(0)*Z(1)"
def test_observable_partition_one_set():
pauli1 = PauliString(spec="ZI")
pauli2 = PauliString(spec="IZ")
pauli3 = PauliString(spec="ZZ")
obs = Observable(pauli1, pauli2, pauli3)
assert obs.nterms == 3
assert obs.ngroups == 1
assert obs.groups[0] == PauliStringCollection(pauli1, pauli2, pauli3)
def test_pstringcollection():
x = PauliString(spec="X")
iz = PauliString(spec="IZ")
xz = PauliString(spec="XZ")
xzixx = PauliString(spec="XZIXX")
pauli_collection = PauliStringCollection(x, iz, xz, xzixx)
assert pauli_collection.elements == [x, iz, xz, xzixx]
assert pauli_collection.elements_by_weight == {
1: Counter((x, iz)),
2: Counter((xz,)),
4: Counter((xzixx,)),
}
assert pauli_collection.min_weight() == 1
assert pauli_collection.max_weight() == 4
assert pauli_collection.support() == {0, 1, 3, 4}
assert len(pauli_collection) == 4
def test_pstring_collection_add():
pcol = PauliStringCollection()
a = PauliString(spec="ZZ")
assert pcol.can_add(a)
pcol.add(a)
assert pcol.elements == [a]
b = PauliString(spec="ZIXZ")
assert pcol.can_add(b)
pcol.add(b)
assert pcol.elements == [a, b]
assert pcol.can_add(a)
pcol.add(a)
assert pcol.elements == [a, a, b]
c = PauliString(spec="YY")
assert not pcol.can_add(c)
with pytest.raises(ValueError, match="Cannot add PauliString"):
pcol.add(c)
def partition(self, seed: Optional[int] = None) -> None:
rng = np.random.RandomState(seed)
psets: List[PauliStringCollection] = []
paulis = copy.deepcopy(self._paulis)
rng.shuffle(paulis)
while paulis:
pauli = paulis.pop()
added = False
for (i, pset) in enumerate(psets):
if pset.can_add(pauli):
pset.add(pauli)
added = True
break
if not added:
psets.append(PauliStringCollection(pauli))
self._groups = psets
self._ngroups = len(self._groups)