wip Pauli Y support

pyzx/gflow.py

@@ -14,6 +14,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+from fractions import Fraction
 from typing import Dict, Set, Tuple, Optional
 
 from .extract import bi_adj
@@ -76,7 +77,8 @@ def gflow(
     vertices: Set[VT] = set(v for v in g.vertices() if vertex_is_zx(ty[v]))
     pattern_inputs: Set[VT] = set()
     pattern_outputs: Set[VT] = set()
-    paulis: Set[VT] = set()
+    pauli_x: Set[VT] = set()
+    pauli_y: Set[VT] = set()
 
     for inp in g.inputs():
         pattern_inputs |= set(n for n in g.neighbors(inp) if vertex_is_zx(ty[n]))
@@ -87,7 +89,8 @@ def gflow(
         pattern_inputs, pattern_outputs = pattern_outputs, pattern_inputs
 
     if pauli:
-        paulis = set(v for v in vertices.difference(pattern_inputs) if g.phase(v) in (0,1))
+        pauli_x = set(v for v in vertices if g.phase(v) in (0,1))
+        pauli_y = set(v for v in vertices if g.phase(v) in (Fraction(1,2),Fraction(-1,2)))
 
     processed: Set[VT] = pattern_outputs.copy() | g.grounds()
     non_outputs = list(vertices.difference(pattern_outputs))
@@ -100,7 +103,7 @@ def gflow(
         correct: Set[VT] = set()
         processed_prime = [
             v
-            for v in (processed | paulis).difference(pattern_inputs)
+            for v in (processed | pauli_x | pauli_y).difference(pattern_inputs)
             if focus or any(w not in processed for w in g.neighbors(v))
         ]