The graph-like simplification strategies now automatically enable the…

… auto edge-toggling for Multigraph. Helps with zxlive#256

pyzx/graph/multigraph.py

@@ -69,7 +69,7 @@ def __init__(self) -> None:
         self._auto_simplify: bool                       = True
         self._vindex: int                               = 0
         self.nedges: int                                = 0
-        self.ty: Dict[int,VertexType]              = dict()
+        self.ty: Dict[int,VertexType]                   = dict()
         self._phase: Dict[int, FractionLike]            = dict()
         self._qindex: Dict[int, FloatInt]               = dict()
         self._maxq: FloatInt                            = -1
@@ -108,6 +108,9 @@ def set_auto_simplify(self, s: bool):
         """Automatically remove parallel edges as edges are added"""
         self._auto_simplify = s
 
+    def get_auto_simplify(self):
+        return self._auto_simplify
+
     def multigraph(self):
         return False
 

pyzx/simplify.py

@@ -27,12 +27,14 @@
         'full_reduce', 'teleport_reduce', 'reduce_scalar', 'supplementarity_simp',
         'to_clifford_normal_form_graph', 'to_graph_like', 'is_graph_like']
 
+from ast import Mult
 from optparse import Option
 from typing import List, Callable, Optional, Union, Generic, Tuple, Dict, Iterator, cast
 
 from .utils import EdgeType, VertexType, toggle_edge, vertex_is_zx, toggle_vertex
 from .rules import *
 from .graph.base import BaseGraph, VT, ET
+from .graph.multigraph import Multigraph
 from .circuit import Circuit
 
 class Stats(object):
@@ -58,6 +60,7 @@ def simp(
     name: str,
     match: Callable[..., List[MatchObject]],
     rewrite: Callable[[BaseGraph[VT,ET],List[MatchObject]],RewriteOutputType[VT,ET]],
+    auto_simplify_parallel_edges: bool = False,
     matchf:Optional[Union[Callable[[ET],bool], Callable[[VT],bool]]]=None,
     quiet:bool=False,
     stats:Optional[Stats]=None) -> int:
@@ -73,13 +76,17 @@ def simp(
         str name: The name to display if ``quiet`` is set to False.
         match: One of the ``match_*`` functions of rules_.
         rewrite: One of the rewrite functions of rules_.
+        auto_simplify_parallel_edges: whether to automatically combine parallel edges between vertices if the graph is a Multigraph
         matchf: An optional filtering function on candidate vertices or edges, which
            is passed as the second argument to the match function.
         quiet: Suppress output on numbers of matches found during simplification.
 
     Returns:
         Number of iterations of ``rewrite`` that had to be applied before no more matches were found."""
 
+    if auto_simplify_parallel_edges and isinstance(g, Multigraph):
+        auto_simp_value = g.get_auto_simplify()
+        g.set_auto_simplify(True)
     i = 0
     new_matches = True
     while new_matches:
@@ -103,19 +110,25 @@ def simp(
             new_matches = True
             if stats is not None: stats.count_rewrites(name, len(m))
     if not quiet and i>0: print(' {!s} iterations'.format(i))
+    if auto_simplify_parallel_edges and isinstance(g, Multigraph):
+        g.set_auto_simplify(auto_simp_value)
     return i
 
 def pivot_simp(g: BaseGraph[VT,ET], matchf:Optional[Callable[[ET],bool]]=None, quiet:bool=False, stats:Optional[Stats]=None) -> int:
-    return simp(g, 'pivot_simp', match_pivot_parallel, pivot, matchf=matchf, quiet=quiet, stats=stats)
+    return simp(g, 'pivot_simp', match_pivot_parallel, pivot, 
+                auto_simplify_parallel_edges=True, matchf=matchf, quiet=quiet, stats=stats)
 
 def pivot_gadget_simp(g: BaseGraph[VT,ET], matchf:Optional[Callable[[ET],bool]]=None, quiet:bool=False, stats:Optional[Stats]=None) -> int:
-    return simp(g, 'pivot_gadget_simp', match_pivot_gadget, pivot, matchf=matchf, quiet=quiet, stats=stats)
+    return simp(g, 'pivot_gadget_simp', match_pivot_gadget, pivot, 
+                auto_simplify_parallel_edges=True, matchf=matchf, quiet=quiet, stats=stats)
 
 def pivot_boundary_simp(g: BaseGraph[VT,ET], matchf:Optional[Callable[[ET],bool]]=None, quiet:bool=False, stats:Optional[Stats]=None) -> int:
-    return simp(g, 'pivot_boundary_simp', match_pivot_boundary, pivot, matchf=matchf, quiet=quiet, stats=stats)
+    return simp(g, 'pivot_boundary_simp', match_pivot_boundary, pivot, 
+                auto_simplify_parallel_edges=True, matchf=matchf, quiet=quiet, stats=stats)
 
 def lcomp_simp(g: BaseGraph[VT,ET], matchf:Optional[Callable[[VT],bool]]=None, quiet:bool=False, stats:Optional[Stats]=None) -> int:
-    return simp(g, 'lcomp_simp', match_lcomp_parallel, lcomp, matchf=matchf, quiet=quiet, stats=stats)
+    return simp(g, 'lcomp_simp', match_lcomp_parallel, lcomp, 
+                auto_simplify_parallel_edges=True, matchf=matchf, quiet=quiet, stats=stats)
 
 def bialg_simp(g: BaseGraph[VT,ET], quiet:bool=False, stats: Optional[Stats]=None) -> int:
     return simp(g, 'bialg_simp', match_bialg_parallel, bialg, quiet=quiet, stats=stats)
@@ -127,10 +140,12 @@ def id_simp(g: BaseGraph[VT,ET], matchf:Optional[Callable[[VT],bool]]=None, quie
     return simp(g, 'id_simp', match_ids_parallel, remove_ids, matchf=matchf, quiet=quiet, stats=stats)
 
 def gadget_simp(g: BaseGraph[VT,ET], matchf: Optional[Callable[[VT],bool]]=None, quiet:bool=False, stats:Optional[Stats]=None) -> int:
-    return simp(g, 'gadget_simp', match_phase_gadgets, merge_phase_gadgets, matchf=matchf, quiet=quiet, stats=stats)
+    return simp(g, 'gadget_simp', match_phase_gadgets, merge_phase_gadgets, 
+                auto_simplify_parallel_edges=True, matchf=matchf, quiet=quiet, stats=stats)
 
 def supplementarity_simp(g: BaseGraph[VT,ET], quiet:bool=False, stats:Optional[Stats]=None) -> int:
-    return simp(g, 'supplementarity_simp', match_supplementarity, apply_supplementarity, quiet=quiet, stats=stats)
+    return simp(g, 'supplementarity_simp', match_supplementarity, apply_supplementarity, 
+                auto_simplify_parallel_edges=True, quiet=quiet, stats=stats)
 
 def copy_simp(g: BaseGraph[VT,ET], quiet:bool=False, stats:Optional[Stats]=None) -> int:
     """Copies 1-ary spiders with 0/pi phase through neighbors.