Reduce mypy errors in paulis.py

[rht]

Description

This currently reduces the mypy error from 31 down to 20. For the rest, I am not so sure how to handle them.

Checklist

• The above description motivates these changes.
• All new and existing tests pass locally and on Travis CI.
• Parameters and return values have type hints with PEP 484 syntax.
• Functions and classes have useful Sphinx-style docstrings.
• All code follows Black style and obeys flake8 conventions.
• The changelog is updated, including author and PR number (@username, gh-xxx).

[appleby]

These changes look basically sane to me. Couple of small changes requested. I think getting this file down to zero errors can happen in a separate PR.

[appleby]

It looks like the travis build failed in make check-types. ~ 13 errors related to type changes here, mostly in the pyquil/experiment and pyquil/simulation modules.

[karalekas]

@rht apply this diff to squash the remaining mypy errors, and fix the changelog conflict, and this is good to go

diff --git a/pyquil/experiment/_group.py b/pyquil/experiment/_group.py
index e0c9389..1103bbe 100644
--- a/pyquil/experiment/_group.py
+++ b/pyquil/experiment/_group.py
@@ -189,6 +189,7 @@ def _max_weight_operator(ops: Iterable[PauliTerm]) -> Union[None, PauliTerm]:
     mapping = dict()  # type: Dict[int, str]
     for op in ops:
         for idx, op_str in op:
+            assert isinstance(idx, int)
             if idx in mapping:
                 if mapping[idx] != op_str:
                     return None
diff --git a/pyquil/experiment/_main.py b/pyquil/experiment/_main.py
index a1b1ec8..ff790ff 100644
--- a/pyquil/experiment/_main.py
+++ b/pyquil/experiment/_main.py
@@ -286,7 +286,7 @@ class TomographyExperiment:
         """
         meas_qubits: Set[int] = set()
         for settings in self:
-            meas_qubits.update(settings[0].out_operator.get_qubits())
+            meas_qubits.update(cast(List[int], settings[0].out_operator.get_qubits()))
         return sorted(meas_qubits)
 
     def get_meas_registers(self, qubits: Optional[Sequence[int]] = None) -> List[int]:
@@ -377,8 +377,12 @@ class TomographyExperiment:
         """
         meas_qubits = self.get_meas_qubits()
 
-        in_pt = PauliTerm.from_list([(op, meas_qubits.index(q)) for q, op in setting.in_operator])
-        out_pt = PauliTerm.from_list([(op, meas_qubits.index(q)) for q, op in setting.out_operator])
+        in_pt = PauliTerm.from_list(
+            [(op, meas_qubits.index(cast(int, q))) for q, op in setting.in_operator]
+        )
+        out_pt = PauliTerm.from_list(
+            [(op, meas_qubits.index(cast(int, q))) for q, op in setting.out_operator]
+        )
 
         preparation_map = pauli_term_to_preparation_memory_map(in_pt)
         measurement_map = pauli_term_to_measurement_memory_map(out_pt)
diff --git a/pyquil/experiment/_memory.py b/pyquil/experiment/_memory.py
index ddf693d..0a54e58 100644
--- a/pyquil/experiment/_memory.py
+++ b/pyquil/experiment/_memory.py
@@ -15,7 +15,7 @@
 ##############################################################################
 
 import itertools
-from typing import Dict, List, Tuple
+from typing import Dict, List, Tuple, cast
 
 import numpy as np
 
@@ -102,7 +102,7 @@ def pauli_term_to_euler_memory_map(
     gamma_label = f"{prefix}_{suffix_gamma}"
 
     # assume the pauli indices are equivalent to the memory region
-    memory_size = max(term.get_qubits()) + 1
+    memory_size = max(cast(List[int], term.get_qubits())) + 1
 
     memory_map = {
         alpha_label: [0.0] * memory_size,
@@ -113,6 +113,7 @@ def pauli_term_to_euler_memory_map(
     tuples = {"X": tuple_x, "Y": tuple_y, "Z": tuple_z, "I": tuple_z}
 
     for qubit, operator in term:
+        assert isinstance(qubit, int)
         if operator not in tuples:
             raise ValueError(f"Unknown operator {operator}")
         memory_map[alpha_label][qubit] = tuples[operator][0]
diff --git a/pyquil/experiment/_setting.py b/pyquil/experiment/_setting.py
index 37c1bda..05186a7 100644
--- a/pyquil/experiment/_setting.py
+++ b/pyquil/experiment/_setting.py
@@ -123,7 +123,7 @@ def _pauli_to_product_state(in_state: PauliTerm) -> TensorProductState:
     else:
         return TensorProductState(
             [
-                _OneQState(label=pauli_label, index=0, qubit=qubit)
+                _OneQState(label=pauli_label, index=0, qubit=cast(int, qubit))
                 for qubit, pauli_label in in_state._ops.items()
             ]
         )
diff --git a/pyquil/simulation/_numpy.py b/pyquil/simulation/_numpy.py
index bd39c10..b275256 100644
--- a/pyquil/simulation/_numpy.py
+++ b/pyquil/simulation/_numpy.py
@@ -166,6 +166,7 @@ def _term_expectation(wf: np.ndarray, term: PauliTerm) -> Any:
     # Computes <psi|XYZ..XXZ|psi>
     wf2 = wf
     for qubit_i, op_str in term._ops.items():
+        assert isinstance(qubit_i, int)
         # Re-use QUANTUM_GATES since it has X, Y, Z
         op_mat = QUANTUM_GATES[op_str]
         wf2 = targeted_tensordot(gate=op_mat, wf=wf2, wf_target_inds=[qubit_i])
diff --git a/pyquil/simulation/_reference.py b/pyquil/simulation/_reference.py
index 437a3c1..30f1f83 100644
--- a/pyquil/simulation/_reference.py
+++ b/pyquil/simulation/_reference.py
@@ -30,6 +30,7 @@ def _term_expectation(wf: np.ndarray, term: PauliTerm, n_qubits: int) -> Any:
     # Computes <psi|XYZ..XXZ|psi>
     wf2 = wf
     for qubit_i, op_str in term._ops.items():
+        assert isinstance(qubit_i, int)
         # Re-use QUANTUM_GATES since it has X, Y, Z
         op_mat = QUANTUM_GATES[op_str]
         op_mat = lifted_gate_matrix(matrix=op_mat, qubit_inds=[qubit_i], n_qubits=n_qubits)

[rht]

@karalekas applied the diff in the 4th commit.

[rht]

The CI failure is due to docs/source/migration.ipynb.

[karalekas]

Figured out the issue -- nbformat v5.0.0 and v5.0.1 are broken, had to wait for them to fix it. Should be g2g soon.

[appleby]

lgtm.