def _from_label(label):
"""Return the symplectic representation of a Pauli stabilizer string"""
# Check if first character is '+' or '-'
phase = False
if label[0] in ['-', '+']:
phase = (label[0] == '-')
label = label[1:]
return PauliTable._from_label(label), phase
def from_list(obj):
"""Construct from a list [(pauli_str, coeffs)]"""
obj = list(obj) # To convert zip or other iterable
num_qubits = len(PauliTable._from_label(obj[0][0]))
size = len(obj)
coeffs = np.zeros(size, dtype=complex)
labels = np.zeros(size, dtype='<U{}'.format(num_qubits))
for i, item in enumerate(obj):
labels[i] = item[0]
coeffs[i] = item[1]
table = PauliTable.from_labels(labels)
return SparsePauliOp(table, coeffs)
