Use f-strings instead of percent operator or str.format() (#6198)

Convert all `%` and `str.format()` expressions or disable pylint
check where `str.format()` is more readable.

Partially fixes #6171

cirq-core/cirq/circuits/_block_diagram_drawer_test.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 import itertools
 
 import pytest
@@ -35,13 +32,13 @@ def _assert_same_diagram(actual: str, expected: str):
         "Diagram differs from the desired diagram.\n"
         '\n'
         'Actual diagram:\n'
-        '{}\n'
+        f'{actual}\n'
         '\n'
         'Desired diagram:\n'
-        '{}\n'
+        f'{expected}\n'
         '\n'
         'Highlighted differences:\n'
-        '{}\n'.format(actual, expected, cirq.testing.highlight_text_differences(actual, expected))
+        f'{cirq.testing.highlight_text_differences(actual, expected)}\n'
     )
 
 

cirq-core/cirq/circuits/circuit_operation.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 """A structure for encapsulating entire circuits in an operation.
 
 A CircuitOperation is an Operation object that wraps a FrozenCircuit. When
@@ -463,9 +460,7 @@ def __str__(self):
         # TODO: support out-of-line subcircuit definition in string format.
         msg_lines = str(self.circuit).split('\n')
         msg_width = max([len(line) for line in msg_lines])
-        circuit_msg = '\n'.join(
-            '[ {line:<{width}} ]'.format(line=line, width=msg_width) for line in msg_lines
-        )
+        circuit_msg = '\n'.join(f'[ {line:<{msg_width}} ]' for line in msg_lines)
         args = []
 
         def dict_str(d: Mapping) -> str:

cirq-core/cirq/circuits/text_diagram_drawer_test.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 from unittest import mock
 import pytest
 
@@ -49,17 +46,13 @@ def assert_has_rendering(actual: TextDiagramDrawer, desired: str, **kwargs) -> N
         "Diagram's rendering differs from the desired rendering.\n"
         '\n'
         'Actual rendering:\n'
-        '{}\n'
+        f'{actual_diagram}\n'
         '\n'
         'Desired rendering:\n'
-        '{}\n'
+        f'{desired_diagram}\n'
         '\n'
         'Highlighted differences:\n'
-        '{}\n'.format(
-            actual_diagram,
-            desired_diagram,
-            ct.highlight_text_differences(actual_diagram, desired_diagram),
-        )
+        f'{ct.highlight_text_differences(actual_diagram, desired_diagram)}\n'
     )
 
 

cirq-core/cirq/contrib/acquaintance/bipartite.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 import enum
 import itertools
 from typing import Dict, Sequence, Tuple, Union, TYPE_CHECKING
@@ -136,7 +133,7 @@ def _circuit_diagram_info_(self, args: 'cirq.CircuitDiagramInfoArgs') -> Tuple[s
         if self.subgraph == BipartiteGraphType.MATCHING:
             name = 'Matching'
         elif self.subgraph == BipartiteGraphType.COMPLETE:
-            name = 'K_{{{0}, {0}}}'.format(self.part_size)
+            name = f'K_{{{self.part_size}, {self.part_size}}}'
         # NB: self.subgraph not in BipartiteGraphType caught by self.permutation
         arrow = '↦' if args.use_unicode_characters else '->'
 

cirq-core/cirq/contrib/acquaintance/devices.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 from typing import Union, TYPE_CHECKING
 
 import abc
@@ -39,8 +36,8 @@ def validate_operation(self, operation: 'cirq.Operation') -> None:
             isinstance(operation, ops.GateOperation) and isinstance(operation.gate, self.gate_types)
         ):
             raise ValueError(
-                'not (isinstance({0!r}, {1!r}) and '
-                'ininstance({0!r}.gate, {2!r})'.format(operation, ops.Operation, self.gate_types)
+                f'not (isinstance({operation!r}, {ops.Operation!r}) and '
+                f'ininstance({operation!r}.gate, {self.gate_types!r})'
             )
 
 

cirq-core/cirq/contrib/acquaintance/gates.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 import functools
 import itertools
 import math
@@ -350,8 +347,9 @@ def permutation(self) -> Dict[int, int]:
         return {i: j for i, j in enumerate(reversed(range(sum(self.part_lens))))}
 
     def __repr__(self) -> str:
-        return 'cirq.contrib.acquaintance.SwapNetworkGate({!r}, {!r})'.format(
-            self.part_lens, self.acquaintance_size
+        return (
+            'cirq.contrib.acquaintance.SwapNetworkGate('
+            f'{self.part_lens!r}, {self.acquaintance_size!r})'
         )
 
     def _value_equality_values_(self):

cirq-core/cirq/contrib/acquaintance/testing.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 from typing import cast, Sequence, TYPE_CHECKING
 
 from cirq import devices, ops, protocols
@@ -32,13 +29,11 @@ def assert_permutation_decomposition_equivalence(gate: PermutationGate, n_qubits
     update_mapping(mapping, operations)
     expected_mapping = {qubits[j]: i for i, j in gate.permutation().items()}
     assert mapping == expected_mapping, (
-        "{!r}.permutation({}) doesn't match decomposition.\n"
+        f"{gate!r}.permutation({n_qubits}) doesn't match decomposition.\n"
         '\n'
         'Actual mapping:\n'
-        '{}\n'
+        f'{[mapping[q] for q in qubits]}\n'
         '\n'
         'Expected mapping:\n'
-        '{}\n'.format(
-            gate, n_qubits, [mapping[q] for q in qubits], [expected_mapping[q] for q in qubits]
-        )
+        f'{[expected_mapping[q] for q in qubits]}\n'
     )

cirq-core/cirq/contrib/paulistring/recombine.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 from typing import Any, Callable, Iterable, Sequence, Tuple, Union, cast, List
 
 from cirq import circuits, ops, protocols
@@ -86,10 +83,9 @@ def move_pauli_strings_into_circuit(
         # Pick the Pauli string that can be moved furthest through
         # the Clifford circuit
         for best_string_op, best_index, best_node in placements:
-            assert (
-                best_index <= last_index
-            ), "Unexpected insertion index order, {} >= {}, len: {}".format(
-                best_index, last_index, len(output_ops)
+            assert best_index <= last_index, (
+                "Unexpected insertion index order, "
+                f"{best_index} >= {last_index}, len: {len(output_ops)}"
             )
 
             last_index = best_index

cirq-core/cirq/contrib/qasm_import/_parser.py

@@ -12,9 +12,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# TODO(#6171): enable the check and fix pylint errors
-# pylint: disable=consider-using-f-string
-
 import functools
 import operator
 from typing import Any, Callable, cast, Dict, Iterable, List, Optional, Union, TYPE_CHECKING
@@ -86,16 +83,15 @@ def __init__(
     def _validate_args(self, args: List[List[ops.Qid]], lineno: int):
         if len(args) != self.num_args:
             raise QasmException(
-                "{} only takes {} arg(s) (qubits and/or registers), "
-                "got: {}, at line {}".format(self.qasm_gate, self.num_args, len(args), lineno)
+                f"{self.qasm_gate} only takes {self.num_args} arg(s) (qubits and/or registers), "
+                f"got: {len(args)}, at line {lineno}"
             )
 
     def _validate_params(self, params: List[float], lineno: int):
         if len(params) != self.num_params:
             raise QasmException(
-                "{} takes {} parameter(s), got: {}, at line {}".format(
-                    self.qasm_gate, self.num_params, len(params), lineno
-                )
+                f"{self.qasm_gate} takes {self.num_params} parameter(s), "
+                f"got: {len(params)}, at line {lineno}"
             )
 
     def on(
@@ -291,8 +287,7 @@ def p_format(self, p):
         """format : FORMAT_SPEC"""
         if p[1] != "2.0":
             raise QasmException(
-                "Unsupported OpenQASM version: {}, "
-                "only 2.0 is supported currently by Cirq".format(p[1])
+                f"Unsupported OpenQASM version: {p[1]}, only 2.0 is supported currently by Cirq"
             )
 
     # circuit : new_reg circuit
@@ -349,11 +344,8 @@ def _resolve_gate_operation(
     ):
         gate_set = self.basic_gates if not self.qelibinc else self.all_gates
         if gate not in gate_set.keys():
-            msg = 'Unknown gate "{}" at line {}{}'.format(
-                gate,
-                p.lineno(1),
-                ", did you forget to include qelib1.inc?" if not self.qelibinc else "",
-            )
+            tip = ", did you forget to include qelib1.inc?" if not self.qelibinc else ""
+            msg = f'Unknown gate "{gate}" at line {p.lineno(1)}{tip}'
             raise QasmException(msg)
         p[0] = gate_set[gate].on(args=args, params=params, lineno=p.lineno(1))
 
@@ -464,9 +456,9 @@ def p_quantum_arg_bit(self, p):
         size = self.qregs[reg]
         if idx >= size:
             raise QasmException(
-                'Out of bounds qubit index {} '
-                'on register {} of size {} '
-                'at line {}'.format(idx, reg, size, p.lineno(1))
+                f'Out of bounds qubit index {idx} '
+                f'on register {reg} of size {size} '
+                f'at line {p.lineno(1)}'
             )
         if arg_name not in self.qubits.keys():
             self.qubits[arg_name] = NamedQubit(arg_name)
@@ -483,9 +475,9 @@ def p_classical_arg_bit(self, p):
         size = self.cregs[reg]
         if idx >= size:
             raise QasmException(
-                'Out of bounds bit index {} '
-                'on classical register {} of size {} '
-                'at line {}'.format(idx, reg, size, p.lineno(1))
+                f'Out of bounds bit index {idx} '
+                f'on classical register {reg} of size {size} '
+                f'at line {p.lineno(1)}'
             )
         p[0] = [arg_name]
 
@@ -499,8 +491,8 @@ def p_measurement(self, p):
 
         if len(qreg) != len(creg):
             raise QasmException(
-                'mismatched register sizes {} -> {} for measurement '
-                'at line {}'.format(len(qreg), len(creg), p.lineno(1))
+                f'mismatched register sizes {len(qreg)} -> {len(creg)} for measurement '
+                f'at line {p.lineno(1)}'
             )
 
         p[0] = [