Fixes gpindices initialization issue in TPPOVM.

Plumbs the 'called_from_reduce' argument of TPPOVM.__init__ into
ComplementPOVMEffect and ConjugatedStatePOVMEffect so that effect
gpindices aren't allocated during the intialization of a TPPOVM
that originates via a __reduce__ call.  Also adds logic to BasePOVM
to avoid copying effect vectors, which would reset their gpindices
and cause allocation down the line.  This bugfix may also fix issues
with copying TPPOVM objects via, e.g., deepcopy, as this uses the
same control path as pickle.  Lightly tested on a 1Q TP-parameterized
model.

pygsti/modelmembers/povms/basepovm.py

@@ -75,7 +75,10 @@ def __init__(self, effects, evotype=None, state_space=None, preserve_sum=False,
         paramlbls = []
         for k, v in items:
             if k == self.complement_label: continue
-            if isinstance(v, _POVMEffect):
+            if called_from_reduce:  # __reduce__ should always initialize w/POVMEffects except for ...
+                assert isinstance(v, _POVMEffect)  # complement (which hits continue above)
+                effect = v  # don't copy as we want to preserve the gpindices in effects
+            elif isinstance(v, _POVMEffect):
                 effect = v if (not preserve_sum) else v.copy()  # .copy() just to de-allocate parameters
             else:
                 assert(evotype is not None), "Must specify `evotype` when effect vectors are not POVMEffect objects!"
@@ -108,7 +111,7 @@ def __init__(self, effects, evotype=None, state_space=None, preserve_sum=False,
             identity_for_complement = _np.array(sum([v.to_dense().reshape(comp_val.shape) for v in non_comp_effects])
                                                 + comp_val, 'd')  # ensure shapes match before summing
             complement_effect = _ComplementPOVMEffect(
-                identity_for_complement, non_comp_effects)
+                identity_for_complement, non_comp_effects, called_from_reduce)
             items.append((self.complement_label, complement_effect))
 
         super(_BasePOVM, self).__init__(state_space, evotype, None, items)

pygsti/modelmembers/povms/complementeffect.py

@@ -43,7 +43,7 @@ class ComplementPOVMEffect(_ConjugatedStatePOVMEffect):
         "complement" POVM effect vector.
     """
 
-    def __init__(self, identity, other_effects):
+    def __init__(self, identity, other_effects, called_from_reduce=False):
         evotype = other_effects[0]._evotype
         state_space = other_effects[0].state_space
 
@@ -62,8 +62,11 @@ def __init__(self, identity, other_effects):
         # 2) set the gpindices of the elements of other_spamvecs so
         #    that they index into our local parameter vector.
 
-        _ConjugatedStatePOVMEffect.__init__(self, self.identity.copy())
-        self.init_gpindices()  # initialize our gpindices based on sub-members
+        _ConjugatedStatePOVMEffect.__init__(self, self.identity.copy(), called_from_reduce)
+        if not called_from_reduce:
+            self.init_gpindices()  # initialize our gpindices based on sub-members
+        else:
+            self.allocate_gpindices(10000, None, submembers_already_allocated=True)
         self._construct_vector()  # reset's self.base
 
     def _construct_vector(self):

pygsti/modelmembers/povms/conjugatedeffect.py

@@ -139,12 +139,15 @@ class ConjugatedStatePOVMEffect(DenseEffectInterface, _POVMEffect):
         i.e, a (dim,1)-shaped array.
     """
 
-    def __init__(self, state):
+    def __init__(self, state, called_from_reduce=False):
         self.state = state
         evotype = state._evotype
         rep = evotype.create_conjugatedstate_effect_rep(state._rep)
         _POVMEffect.__init__(self, rep, evotype)
-        self.init_gpindices()  # initialize our gpindices based on sub-members
+        if not called_from_reduce:
+            self.init_gpindices()  # initialize our gpindices based on sub-members
+        else:
+            self.allocate_gpindices(10000, None, submembers_already_allocated=True)
 
     @property
     def _basis(self):