Specs dict fix (#4286)

* Add copy function to SpecsDict. * black * Adjust docs to not throw warnings from deprecated specs keys. * Formatting fix. * update doc string * update doc string --------- Co-authored-by: Jay Soni <[email protected]> Co-authored-by: Matthew Silverman <[email protected]>
PennyLaneAI · Jun 23, 2023 · d9779ed · d9779ed
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diff --git a/doc/development/deprecations.rst b/doc/development/deprecations.rst
@@ -132,7 +132,7 @@ Completed deprecation cycles
   - Deprecated in v0.29
   - Removed in v0.31
 
-* ``qml.op_sum``` has been removed. Users should use ``qml.sum`` instead.
+* ``qml.op_sum`` has been removed. Users should use ``qml.sum`` instead.
 
   - Deprecated in v0.29.
   - Removed in v0.31.

diff --git a/pennylane/tape/qscript.py b/pennylane/tape/qscript.py
@@ -1428,6 +1428,10 @@ def __getitem__(self, item):
             )
         return super().__getitem__(item)
 
+    def copy(self):
+        """Custom copy function to return a SpecsDict instead of a dict."""
+        return SpecsDict(self.items())
+
 
 def make_qscript(fn, shots: Optional[Union[int, Sequence, Shots]] = None):
     """Returns a function that generates a qscript from a quantum function without any

diff --git a/pennylane/transforms/optimization/pattern_matching.py b/pennylane/transforms/optimization/pattern_matching.py
@@ -141,10 +141,10 @@ def circuit():
     In our case, it is possible to find three CNOTs and replace this pattern with only two CNOTs and therefore
     optimizing the circuit. The number of CNOTs in the circuit is reduced by one.
 
-    >>> qml.specs(qnode)()["gate_types"]["CNOT"]
+    >>> qml.specs(qnode)()["resources"].gate_types["CNOT"]
     4
 
-    >>> qml.specs(optimized_qnode)()["gate_types"]["CNOT"]
+    >>> qml.specs(optimized_qnode)()["resources"].gate_types["CNOT"]
     3
 
     >>> print(qml.draw(qnode)())

diff --git a/pennylane/transforms/specs.py b/pennylane/transforms/specs.py
@@ -88,20 +88,23 @@ def specs_qnode(*args, **kwargs):
         """Returns information on the structure and makeup of provided QNode.
 
         Dictionary keys:
-            * ``"num_operations"``
-            * ``"num_observables"``
-            * ``"num_diagonalizing_gates"``
-            * ``"gate_sizes"``: dictionary mapping gate number of wires to number of occurances
-            * ``"gate_types"``: dictionary mapping gate types to number of occurances
+            * ``"num_operations"`` number of operations in the qnode
+            * ``"num_observables"`` number of observables in the qnode
+            * ``"num_diagonalizing_gates"`` number of diagonalizing gates required for execution of the qnode
+            * ``"resources"``: a :class:`~.resource.Resources` object containing resource quantities used by the qnode
             * ``"num_used_wires"``: number of wires used by the circuit
             * ``"num_device_wires"``: number of wires in device
             * ``"depth"``: longest path in directed acyclic graph representation
-            * ``"dev_short_name"``: name of QNode device
-            * ``"diff_method"``
+            * ``"device_name"``: name of QNode device
+            * ``"expansion_strategy"``: string specifying method for decomposing operations in the circuit
+            * ``"gradient_options"``: additional configurations for gradient computations
+            * ``"interface"``: autodiff framework to dispatch to for the qnode execution
+            * ``"diff_method"``: a string specifying the differntiation method
+            * ``"gradient_fn"``: executable to compute the gradient of the qnode
 
         Potential Additional Information:
             * ``"num_trainable_params"``: number of individual scalars that are trainable
-            * ``"num_parameter_shift_executions"``: number of times circuit will execute when
+            * ``"num_gradient_executions"``: number of times circuit will execute when
                     calculating the derivative
 
         Returns:

diff --git a/tests/tape/test_qscript.py b/tests/tape/test_qscript.py
@@ -468,6 +468,16 @@ def test_specs_tape(self, make_script):
         assert specs["num_trainable_params"] == 5
         assert specs["depth"] == 3
 
+    def test_specs_copy(self, make_script):
+        """Test that the copy method of specs retuns a SpecsDict."""
+        qs = make_script
+        copied_specs = qs.specs.copy()
+
+        assert isinstance(copied_specs, qml.tape.qscript.SpecsDict)
+        with pytest.warns(UserWarning, match="key is deprecated and will be removed"):
+            for k, v in qs.specs.items():
+                assert copied_specs[k] == v
+
     @pytest.mark.parametrize(
         "shots, total_shots, shot_vector",
         [