refactor!: remove StateTransitionCollection

docs/usage/reaction.ipynb

@@ -466,7 +466,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "io.asdict(reaction.transition_groups[0].topology)"
+    "io.asdict(reaction.transitions[0].topology)"
    ]
   },
   {

src/qrules/__init__.py

@@ -366,10 +366,10 @@ def generate_transitions(  # pylint: disable=too-many-arguments
     ...     particle_db=qrules.load_pdg(),
     ...     topology_building="isobar",
     ... )
-    >>> len(reaction.transition_groups)
-    3
     >>> len(reaction.transitions)
     4
+    >>> len(reaction.group_by_topology())
+    3
     """
     if isinstance(initial_state, str) or (
         isinstance(initial_state, tuple)

src/qrules/io/__init__.py

@@ -16,13 +16,7 @@
 
 from qrules.particle import Particle, ParticleCollection
 from qrules.topology import StateTransitionGraph, Topology
-from qrules.transition import (
-    ProblemSet,
-    ReactionInfo,
-    State,
-    StateTransition,
-    StateTransitionCollection,
-)
+from qrules.transition import ProblemSet, ReactionInfo, State, StateTransition
 
 from . import _dict, _dot
 
@@ -33,10 +27,7 @@ def asdict(instance: object) -> dict:
         return _dict.from_particle(instance)
     if isinstance(instance, ParticleCollection):
         return _dict.from_particle_collection(instance)
-    if isinstance(
-        instance,
-        (ReactionInfo, State, StateTransition, StateTransitionCollection),
-    ):
+    if isinstance(instance, (ReactionInfo, State, StateTransition)):
         return attrs.asdict(
             instance,
             recurse=True,
@@ -59,12 +50,10 @@ def fromdict(definition: dict) -> object:
         return _dict.build_particle(definition)
     if keys == {"particles"}:
         return _dict.build_particle_collection(definition)
-    if keys == {"transition_groups", "formalism"}:
+    if keys == {"transitions", "formalism"}:
         return _dict.build_reaction_info(definition)
     if keys == {"topology", "states", "interactions"}:
         return _dict.build_state_transition(definition)
-    if keys == {"transitions"}:
-        return _dict.build_stc(definition)
     if keys == {"topology", "edge_props", "node_props"}:
         return _dict.build_stg(definition)
     if keys == __REQUIRED_TOPOLOGY_FIELDS:
@@ -153,7 +142,7 @@ def asdot(
             node_style=node_style,
         )
         return _dot.insert_graphviz_styling(dot, graphviz_attrs=figure_style)
-    if isinstance(instance, (ReactionInfo, StateTransitionCollection)):
+    if isinstance(instance, ReactionInfo):
         instance = instance.to_graphs()
     if isinstance(instance, abc.Iterable):
         dot = _dot.graph_list_to_dot(

src/qrules/io/_dict.py

@@ -17,12 +17,7 @@
 )
 from qrules.quantum_numbers import InteractionProperties
 from qrules.topology import Edge, StateTransitionGraph, Topology
-from qrules.transition import (
-    ReactionInfo,
-    State,
-    StateTransition,
-    StateTransitionCollection,
-)
+from qrules.transition import ReactionInfo, State, StateTransition
 
 
 def from_particle_collection(particles: ParticleCollection) -> dict:
@@ -79,7 +74,7 @@ def _value_serializer(  # pylint: disable=unused-argument
             return {k: v.name for k, v in value.items()}
         return dict(value)
     if not isinstance(
-        inst, (ReactionInfo, State, StateTransition, StateTransitionCollection)
+        inst, (ReactionInfo, State, StateTransition)
     ) and isinstance(value, Particle):
         return value.name
     if isinstance(value, Parity):
@@ -114,13 +109,11 @@ def build_particle(definition: dict) -> Particle:
 
 
 def build_reaction_info(definition: dict) -> ReactionInfo:
-    transition_groups = [
-        build_stc(graph_def) for graph_def in definition["transition_groups"]
+    transitions = [
+        build_state_transition(transition_def)
+        for transition_def in definition["transitions"]
     ]
-    return ReactionInfo(
-        transition_groups=transition_groups,
-        formalism=definition["formalism"],
-    )
+    return ReactionInfo(transitions, formalism=definition["formalism"])
 
 
 def build_stg(definition: dict) -> StateTransitionGraph[ParticleWithSpin]:
@@ -145,14 +138,6 @@ def build_stg(definition: dict) -> StateTransitionGraph[ParticleWithSpin]:
     )
 
 
-def build_stc(definition: dict) -> StateTransitionCollection:
-    transitions = [
-        build_state_transition(graph_def)
-        for graph_def in definition["transitions"]
-    ]
-    return StateTransitionCollection(transitions=transitions)
-
-
 def build_state_transition(definition: dict) -> StateTransition:
     topology = build_topology(definition["topology"])
     states = {