Rename the pennylane/measure.py file to pennylane/measurements.py

doc/releases/changelog-dev.md

@@ -4,6 +4,13 @@
 
 <h3>New features since last release</h3>
 
+* Added the user-interface for mid-circuit measurements.
+  [(#2236)](https://github.com/PennyLaneAI/pennylane/pull/2236)
+
+* The text based drawer accessed via `qml.draw` has been overhauled. The new drawer has 
+  a `decimals` keyword for controlling parameter rounding, a different algorithm for determining positions, 
+  deprecation of the `charset` keyword, and minor cosmetic changes.
+
 * Transform a circuit from quantum tape, quantum function or quantum node to a pairwise
   commutation DAG (directed acyclic graph). The node represents the quantum operations, and the edges represent 
   non commutation between two operations.
@@ -51,6 +58,7 @@
   >>> second_node_predecessors = second_node.predecessors
   []
   ```
+
 * The text based drawer accessed via `qml.draw` has been overhauled.
   [(#2128)](https://github.com/PennyLaneAI/pennylane/pull/2128)
   [(#2198)](https://github.com/PennyLaneAI/pennylane/pull/2198)

pennylane/__init__.py

@@ -41,7 +41,7 @@
 from pennylane.configuration import Configuration
 from pennylane.tracker import Tracker
 from pennylane.io import *
-from pennylane.measure import density_matrix, expval, probs, sample, state, var
+from pennylane.measurements import density_matrix, expval, probs, sample, state, var
 from pennylane.ops import *
 from pennylane.templates import broadcast, layer
 from pennylane.templates.embeddings import *

pennylane/_device.py

@@ -895,7 +895,7 @@ def check_validity(self, queue, observables):
                 )
 
         for o in observables:
-            if isinstance(o, qml.measure.MeasurementProcess) and o.obs is not None:
+            if isinstance(o, qml.measurements.MeasurementProcess) and o.obs is not None:
                 o = o.obs
 
             if isinstance(o, Tensor):

pennylane/_qubit_device.py

@@ -38,7 +38,7 @@
 from pennylane.math import sum as qmlsum
 from pennylane.wires import Wires
 
-from pennylane.measure import MeasurementProcess
+from pennylane.measurements import MeasurementProcess
 
 
 class QubitDevice(Device):

pennylane/circuit_graph.py

@@ -77,7 +77,7 @@ def _is_returned_observable(op):
         bool: whether or not the observable or measurement process is in the
         return statement
     """
-    is_obs = isinstance(op, (qml.operation.Observable, qml.measure.MeasurementProcess))
+    is_obs = isinstance(op, (qml.operation.Observable, qml.measurements.MeasurementProcess))
     return is_obs and op.return_type is not None
 
 
@@ -151,11 +151,11 @@ def __init__(self, ops, obs, wires, par_info=None, trainable_params=None):
                     # State measurements contain no wires by default, but wires are
                     # required for the circuit drawer, so we recreate the state
                     # measurement with all wires
-                    op = qml.measure.MeasurementProcess(qml.operation.State, wires=wires)
+                    op = qml.measurements.MeasurementProcess(qml.operation.State, wires=wires)
 
                 elif op.return_type is qml.operation.Sample and op.wires == Wires([]):
                     # Sampling without specifying wires is treated as sampling all wires
-                    op = qml.measure.MeasurementProcess(qml.operation.Sample, wires=wires)
+                    op = qml.measurements.MeasurementProcess(qml.operation.Sample, wires=wires)
 
                 op.queue_idx = k
 
@@ -506,7 +506,9 @@ def greedy_layers(self, wire_order=None, show_all_wires=False):
             operations[wire] = list(
                 filter(
                     lambda op: not (
-                        isinstance(op, (qml.operation.Observable, qml.measure.MeasurementProcess))
+                        isinstance(
+                            op, (qml.operation.Observable, qml.measurements.MeasurementProcess)
+                        )
                         and op.return_type is not None
                     ),
                     operations[wire],
@@ -540,7 +542,7 @@ def greedy_layers(self, wire_order=None, show_all_wires=False):
                 observables[wire] = list(
                     filter(
                         lambda op: isinstance(
-                            op, (qml.operation.Observable, qml.measure.MeasurementProcess)
+                            op, (qml.operation.Observable, qml.measurements.MeasurementProcess)
                         )
                         and op.return_type is not None,
                         self._grid[wire],

pennylane/drawer/representation_resolver.py

@@ -328,7 +328,7 @@ def operator_representation(self, op, wire):
         Returns:
             str: String representation of the Operator
         """
-        if isinstance(op, qml.measure.MeasurementProcess):
+        if isinstance(op, qml.measurements.MeasurementProcess):
             if op.obs is not None:
                 op = op.obs
             else:
@@ -511,7 +511,7 @@ def element_representation(self, element, wire):
         if isinstance(element, str):
             return element
         if (
-            isinstance(element, (qml.operation.Observable, qml.measure.MeasurementProcess))
+            isinstance(element, (qml.operation.Observable, qml.measurements.MeasurementProcess))
             and element.return_type is not None
         ):
             return self.output_representation(element, wire)

pennylane/gradients/parameter_shift.py

@@ -317,7 +317,7 @@ def var_param_shift(tape, argnum, shifts=None, gradient_recipes=None, f0=None):
     # Convert all variance measurements on the tape into expectation values
     for i in var_idx:
         obs = expval_tape._measurements[i].obs
-        expval_tape._measurements[i] = qml.measure.MeasurementProcess(
+        expval_tape._measurements[i] = qml.measurements.MeasurementProcess(
             qml.operation.Expectation, obs=obs
         )
 
@@ -357,7 +357,7 @@ def var_param_shift(tape, argnum, shifts=None, gradient_recipes=None, f0=None):
             # We need to calculate d<A^2>/dp; to do so, we replace the
             # involutory observables A in the queue with A^2.
             obs = _square_observable(expval_sq_tape._measurements[i].obs)
-            expval_sq_tape._measurements[i] = qml.measure.MeasurementProcess(
+            expval_sq_tape._measurements[i] = qml.measurements.MeasurementProcess(
                 qml.operation.Expectation, obs=obs
             )
 

pennylane/gradients/parameter_shift_cv.py

@@ -215,7 +215,7 @@ def var_param_shift(tape, dev_wires, argnum=None, shifts=None, gradient_recipes=
     # Convert all variance measurements on the tape into expectation values
     for i in var_idx:
         obs = expval_tape._measurements[i].obs
-        expval_tape._measurements[i] = qml.measure.MeasurementProcess(
+        expval_tape._measurements[i] = qml.measurements.MeasurementProcess(
             qml.operation.Expectation, obs=obs
         )
 
@@ -245,7 +245,7 @@ def var_param_shift(tape, dev_wires, argnum=None, shifts=None, gradient_recipes=
         # with itself, to get a square symmetric matrix representing
         # the square of the observable
         obs = qml.PolyXP(np.outer(A, A), wires=obs.wires)
-        expval_sq_tape._measurements[i] = qml.measure.MeasurementProcess(
+        expval_sq_tape._measurements[i] = qml.measurements.MeasurementProcess(
             qml.operation.Expectation, obs=obs
         )
 
@@ -402,7 +402,7 @@ def second_order_param_shift(tape, dev_wires, argnum=None, shifts=None, gradient
 
             constants.append(constant)
 
-            g_tape._measurements[idx] = qml.measure.MeasurementProcess(
+            g_tape._measurements[idx] = qml.measurements.MeasurementProcess(
                 qml.operation.Expectation, _transform_observable(obs, Z, dev_wires)
             )
 

pennylane/operation.py

@@ -2443,7 +2443,7 @@ def has_unitary_gen(obj):
 @qml.BooleanFn
 def is_measurement(obj):
     """Returns ``True`` if an operator is a ``MeasurementProcess`` instance."""
-    return isinstance(obj, qml.measure.MeasurementProcess)
+    return isinstance(obj, qml.measurements.MeasurementProcess)
 
 
 @qml.BooleanFn

pennylane/qnode.py

@@ -495,7 +495,9 @@ def construct(self, args, kwargs):
         else:
             measurement_processes = self._qfunc_output
 
-        if not all(isinstance(m, qml.measure.MeasurementProcess) for m in measurement_processes):
+        if not all(
+            isinstance(m, qml.measurements.MeasurementProcess) for m in measurement_processes
+        ):
             raise qml.QuantumFunctionError(
                 "A quantum function must return either a single measurement, "
                 "or a nonempty sequence of measurements."

pennylane/qnode_old.py

@@ -586,7 +586,9 @@ def construct(self, args, kwargs):
         else:
             measurement_processes = self.qfunc_output
 
-        if not all(isinstance(m, qml.measure.MeasurementProcess) for m in measurement_processes):
+        if not all(
+            isinstance(m, qml.measurements.MeasurementProcess) for m in measurement_processes
+        ):
             raise qml.QuantumFunctionError(
                 "A quantum function must return either a single measurement, "
                 "or a nonempty sequence of measurements."

pennylane/tape/cv_param_shift.py

@@ -24,7 +24,7 @@
 import numpy as np
 
 import pennylane as qml
-from pennylane.measure import MeasurementProcess
+from pennylane.measurements import MeasurementProcess
 from pennylane.tape import QuantumTape
 
 from .qubit_param_shift import QubitParamShiftTape

pennylane/tape/qubit_param_shift.py

@@ -22,7 +22,7 @@
 import numpy as np
 
 import pennylane as qml
-from pennylane.measure import MeasurementProcess
+from pennylane.measurements import MeasurementProcess
 from pennylane.tape import QuantumTape
 from pennylane.math import toarray
 

pennylane/tape/tape.py

@@ -172,7 +172,7 @@ def expand_tape(tape, depth=1, stop_at=None, expand_measurements=False):
         tape._ops.extend(rotations)
 
         for o, i in zip(diag_obs, tape._obs_sharing_wires_id):
-            new_m = qml.measure.MeasurementProcess(tape.measurements[i].return_type, obs=o)
+            new_m = qml.measurements.MeasurementProcess(tape.measurements[i].return_type, obs=o)
             tape._measurements[i] = new_m
 
     for queue in ("_prep", "_ops", "_measurements"):
@@ -183,15 +183,15 @@ def expand_tape(tape, depth=1, stop_at=None, expand_measurements=False):
             if not expand_measurements:
                 # Measurements should not be expanded; treat measurements
                 # as a stopping condition
-                stop = stop or isinstance(obj, qml.measure.MeasurementProcess)
+                stop = stop or isinstance(obj, qml.measurements.MeasurementProcess)
 
             if stop:
                 # do not expand out the object; append it to the
                 # new tape, and continue to the next object in the queue
                 getattr(new_tape, queue).append(obj)
                 continue
 
-            if isinstance(obj, (qml.operation.Operation, qml.measure.MeasurementProcess)):
+            if isinstance(obj, (qml.operation.Operation, qml.measurements.MeasurementProcess)):
                 # Object is an operation; query it for its expansion
                 try:
                     obj = obj.expand()
@@ -434,7 +434,7 @@ def _process_queue(self):
                 else:
                     self._ops.append(obj)
 
-            elif isinstance(obj, qml.measure.MeasurementProcess):
+            elif isinstance(obj, qml.measurements.MeasurementProcess):
                 # measurement process
                 self._measurements.append(obj)
 

pennylane/transforms/hamiltonian_expand.py

@@ -123,7 +123,7 @@ def hamiltonian_expand(tape, group=True):
     if (
         not isinstance(hamiltonian, qml.Hamiltonian)
         or len(tape.measurements) > 1
-        or tape.measurements[0].return_type != qml.measure.Expectation
+        or tape.measurements[0].return_type != qml.measurements.Expectation
     ):
         raise ValueError(
             "Passed tape must end in `qml.expval(H)`, where H is of type `qml.Hamiltonian`"

pennylane/transforms/qcut.py

@@ -30,7 +30,7 @@
 import pennylane as qml
 from pennylane import apply, expval
 from pennylane.grouping import string_to_pauli_word
-from pennylane.measure import MeasurementProcess
+from pennylane.measurements import MeasurementProcess
 from pennylane.operation import Expectation, Operation, Operator, Tensor
 from pennylane.ops.qubit.non_parametric_ops import WireCut
 from pennylane.tape import QuantumTape

tests/circuit_graph/test_circuit_graph.py

@@ -119,7 +119,7 @@ def lst_mp_equality(lst1, lst2):
         if not isinstance(lst1[index], type(lst2[index])):  # if they are different types
             return False  # then return false
 
-        elif isinstance(lst1[index], qml.measure.MeasurementProcess):
+        elif isinstance(lst1[index], qml.measurements.MeasurementProcess):
             lsts_same = lsts_same and measurement_process_equality(lst1[index], lst2[index])
 
         else:
@@ -308,13 +308,13 @@ def test_grid_when_sample_no_wires(self):
         none are explicitly provided."""
 
         ops = [qml.Hadamard(wires=0), qml.CNOT(wires=[0, 1])]
-        obs_no_wires = [qml.measure.sample(op=None, wires=None)]
-        obs_w_wires = [qml.measure.sample(op=None, wires=[0, 1, 2])]
+        obs_no_wires = [qml.measurements.sample(op=None, wires=None)]
+        obs_w_wires = [qml.measurements.sample(op=None, wires=[0, 1, 2])]
 
         circuit_no_wires = CircuitGraph(ops, obs_no_wires, wires=Wires([0, 1, 2]))
         circuit_w_wires = CircuitGraph(ops, obs_w_wires, wires=Wires([0, 1, 2]))
 
-        sample_w_wires_op = qml.measure.sample(op=None, wires=[0, 1, 2])
+        sample_w_wires_op = qml.measurements.sample(op=None, wires=[0, 1, 2])
         expected_grid = {
             0: [ops[0], ops[1], sample_w_wires_op],
             1: [ops[1], sample_w_wires_op],

tests/devices/test_caching.py

@@ -15,7 +15,7 @@
 import pytest
 
 import pennylane as qml
-from pennylane.measure import expval
+from pennylane.measurements import expval
 from pennylane import qnode, QNode
 from pennylane.devices import DefaultQubit
 from pennylane import numpy as np

tests/drawer/test_circuit_drawer.py

@@ -25,7 +25,7 @@
 from pennylane.drawer.charsets import CHARSETS, UnicodeCharSet, AsciiCharSet
 from pennylane.wires import Wires
 
-from pennylane.measure import state
+from pennylane.measurements import state
 
 
 class TestFunctions:

tests/drawer/test_representation_resolver.py

@@ -20,7 +20,7 @@
 
 import pennylane as qml
 from pennylane.drawer.representation_resolver import RepresentationResolver
-from pennylane.measure import state
+from pennylane.measurements import state
 
 
 @pytest.fixture
@@ -211,8 +211,8 @@ def test_single_parameter_representation(self, unicode_representation_resolver,
             (qml.Toffoli(wires=[0, 2, 1]).inv(), 1, "X⁻¹"),
             (qml.Toffoli(wires=[0, 2, 1]).inv(), 0, "C"),
             (qml.Toffoli(wires=[0, 2, 1]).inv(), 2, "C"),
-            (qml.measure.sample(wires=[0, 1]), 0, "basis"),  # not providing an observable in
-            (qml.measure.sample(wires=[0, 1]), 1, "basis"),  # sample gets displayed as raw
+            (qml.measurements.sample(wires=[0, 1]), 0, "basis"),  # not providing an observable in
+            (qml.measurements.sample(wires=[0, 1]), 1, "basis"),  # sample gets displayed as raw
             (two_wire_quantum_tape(), 0, "QuantumTape:T0"),
             (two_wire_quantum_tape(), 1, "QuantumTape:T0"),
         ],
@@ -355,8 +355,8 @@ def test_operator_representation_unicode(
             (qml.Toffoli(wires=[0, 2, 1]).inv(), 1, "X^-1"),
             (qml.Toffoli(wires=[0, 2, 1]).inv(), 0, "C"),
             (qml.Toffoli(wires=[0, 2, 1]).inv(), 2, "C"),
-            (qml.measure.sample(wires=[0, 1]), 0, "basis"),  # not providing an observable in
-            (qml.measure.sample(wires=[0, 1]), 1, "basis"),  # sample gets displayed as raw
+            (qml.measurements.sample(wires=[0, 1]), 0, "basis"),  # not providing an observable in
+            (qml.measurements.sample(wires=[0, 1]), 1, "basis"),  # sample gets displayed as raw
             (two_wire_quantum_tape(), 0, "QuantumTape:T0"),
             (two_wire_quantum_tape(), 1, "QuantumTape:T0"),
         ],

tests/tape/test_tape.py

@@ -22,7 +22,7 @@
 import pennylane as qml
 from pennylane import CircuitGraph
 from pennylane.tape import QuantumTape
-from pennylane.measure import MeasurementProcess, expval, sample, var
+from pennylane.measurements import MeasurementProcess, expval, sample, var
 
 
 def TestOperationMonkeypatching():

tests/test_measure.py

@@ -22,7 +22,7 @@
 from pennylane.operation import DecompositionUndefinedError
 
 from pennylane.queuing import AnnotatedQueue
-from pennylane.measure import (
+from pennylane.measurements import (
     expval,
     var,
     sample,

tests/test_qubit_device.py

@@ -25,7 +25,7 @@
 from pennylane.circuit_graph import CircuitGraph
 from pennylane.wires import Wires
 from pennylane.tape import QuantumTape
-from pennylane.measure import state
+from pennylane.measurements import state
 
 mock_qubit_device_paulis = ["PauliX", "PauliY", "PauliZ"]
 mock_qubit_device_rotations = ["RX", "RY", "RZ"]
@@ -268,7 +268,7 @@ def test_unsupported_observable_return_type_raise_error(
 
         with qml.tape.QuantumTape() as tape:
             qml.PauliX(wires=0)
-            qml.measure.MeasurementProcess(
+            qml.measurements.MeasurementProcess(
                 return_type="SomeUnsupportedReturnType", obs=qml.PauliZ(0)
             )
 
@@ -615,7 +615,7 @@ def test_sample_with_no_observable_and_no_wires(
     ):
         """Test that when we sample a device without providing an observable or wires then it
         will return the raw samples"""
-        obs = qml.measure.sample(op=None, wires=None)
+        obs = qml.measurements.sample(op=None, wires=None)
         dev = mock_qubit_device_with_original_statistics(wires=2)
         generated_samples = np.array([[1, 0], [1, 1]])
         dev._samples = generated_samples
@@ -628,7 +628,7 @@ def test_sample_with_no_observable_and_with_wires(
     ):
         """Test that when we sample a device without providing an observable but we specify
         wires then it returns the generated samples for only those wires"""
-        obs = qml.measure.sample(op=None, wires=[1])
+        obs = qml.measurements.sample(op=None, wires=[1])
         dev = mock_qubit_device_with_original_statistics(wires=2)
         generated_samples = np.array([[1, 0], [1, 1]])
         dev._samples = generated_samples