Count all 2q vertices

pytket/binders/circuit/Circuit/main.cpp

@@ -544,19 +544,19 @@ void init_circuit(py::module &m) {
           "element of `types`",
           py::arg("types"))
       .def(
-          "depth_by_2q_gates", &Circuit::depth_by_2q_gates,
+          "depth_2q", &Circuit::depth_2q,
           "Returns the number of vertices in the longest path through the "
-          "sub-DAG consisting of vertices representing 2-qubit quantum gates."
-          "Note that box types and conditionals are not included."
+          "sub-DAG consisting of vertices with 2 quantum wires,"
+          "excluding vertices representing barrier operations."
           "\n\n>>> c = Circuit(3)"
           "\n>>> c.CZ(0,1)"
           "\n>>> c.Z(0)"
           "\n>>> c.Z(1)"
           "\n>>> c.ZZMax(1,2)"
           "\n>>> c.CX(1,2)"
-          "\n>>> c.depth_by_2q_gates()"
+          "\n>>> c.depth_2q()"
           "\n3"
-          "\n:return: the circuit depth with respect to 2-qubit quantum gates.")
+          "\n:return: the circuit depth with respect to 2-qubit operations.")
       .def(
           "_to_graphviz_file", &Circuit::to_graphviz_file,
           "Saves a visualisation of a circuit's DAG to a \".dot\" file",

pytket/docs/changelog.rst

@@ -6,7 +6,7 @@ Unreleased
 
 Minor new features:
 
-* Add circuit method ``depth_by_2q_gates``
+* Add circuit method ``depth_2q``
 
 
 1.17.1 (July 2023)

pytket/tests/circuit_test.py

@@ -1024,7 +1024,7 @@ def test_depth() -> None:
     assert c.depth_by_type({OpType.CX, OpType.H}) == 6
     assert c.depth_by_type({OpType.CZ, OpType.H}) == 6
     assert c.depth_by_type(set()) == 0
-    assert c.depth_by_2q_gates() == 6
+    assert c.depth_2q_gates() == 6
 
 
 def test_op_dagger_transpose() -> None:

tket/include/tket/Circuit/Circuit.hpp

@@ -1185,14 +1185,15 @@ class Circuit {
   unsigned depth_by_types(const OpTypeSet &_types) const;
 
   /**
-   * Depth of circuit restricting to 2-qubit quantum gates.
+   * Depth of circuit restricting to 2-qubit operations, excluding barriers.
    *
-   * This is the number of vertices in the longest path through the sub-DAG
-   * consisting of vertices representing 2-qubit operations.
+   * This is the number of vertices in the longest path through the
+   * sub-DAG consisting of vertices with 2 quantum wires,
+   * excluding vertices representing barrier operations.
    *
    * @return depth
    */
-  unsigned depth_by_2q_gates() const;
+  unsigned depth_2q() const;
 
   std::map<Vertex, unit_set_t> vertex_unit_map() const;
   std::map<Vertex, unsigned> vertex_depth_map() const;

tket/src/Circuit/macro_circ_info.cpp

@@ -708,10 +708,10 @@ unsigned Circuit::depth_by_types(const OpTypeSet& _types) const {
   return count;
 }
 
-unsigned Circuit::depth_by_2q_gates() const {
+unsigned Circuit::depth_2q() const {
   unsigned count = 0;
   std::function<bool(Op_ptr)> skip_func = [&](Op_ptr op) {
-    return (op->n_qubits() != 2 || !is_gate_type(op->get_type()));
+    return (op->n_qubits() != 2 || op->get_type() == OpType::Barrier);
   };
   Circuit::SliceIterator slice_iter(*this, skip_func);
   if (!(*slice_iter).empty()) count++;

tket/test/src/Circuit/test_Circ.cpp

@@ -1326,15 +1326,15 @@ SCENARIO("Test depth_by_type method") {
     REQUIRE(circ.depth_by_types({OpType::CX, OpType::CY}) == 2);
   }
 }
-SCENARIO("Test depth_by_2q_gates method") {
+SCENARIO("Test depth_2q_gates method") {
   GIVEN("2q OpTypes") {
     Circuit circ(3, 1);
     circ.add_op<unsigned>(OpType::CX, {0, 1});
     circ.add_op<unsigned>(OpType::Z, {0});
     circ.add_op<unsigned>(OpType::Z, {1});
     circ.add_op<unsigned>(OpType::CZ, {1, 0});
     circ.add_conditional_gate<unsigned>(OpType::CY, {}, {1, 2}, {0}, 0);
-    REQUIRE(circ.depth_by_2q_gates() == 2);
+    REQUIRE(circ.depth_2q() == 3);
   }
   GIVEN("Boxes") {
     Circuit circ(3);
@@ -1343,22 +1343,22 @@ SCENARIO("Test depth_by_2q_gates method") {
     CircBox cbox(inner);
     circ.add_box(cbox, {0, 1});
     circ.add_op<unsigned>(OpType::Z, {1});
-    REQUIRE(circ.depth_by_2q_gates() == 0);
+    REQUIRE(circ.depth_2q() == 1);
   }
   GIVEN("Multi-q gates") {
     Circuit circ(5, 2);
     circ.add_op<unsigned>(OpType::CnX, {0, 1, 2, 4, 3});
     circ.add_op<unsigned>(OpType::CnX, {0, 2});
     circ.add_op<unsigned>(OpType::CnX, {2, 4, 3});
     circ.add_op<unsigned>(OpType::CnX, {3, 4});
-    REQUIRE(circ.depth_by_2q_gates() == 2);
+    REQUIRE(circ.depth_2q() == 2);
   }
   GIVEN("A circuit with other causal links") {
     Circuit circ(4);
     circ.add_op<unsigned>(OpType::CX, {0, 1});
     circ.add_barrier({0, 2});
     circ.add_op<unsigned>(OpType::CZ, {2, 3});
-    REQUIRE(circ.depth_by_2q_gates() == 2);
+    REQUIRE(circ.depth_2q() == 2);
   }
 }