Order of final state influences number of final states

[redeboer]

#145 has introduced a bug: changing the order of the final_state in generate_transitions() can result in a different number of final states. This was determined with git bisect using the following test:

import qrules


def test_order():
    reaction = qrules.generate_transitions(
        initial_state="J/psi(1S)",
        final_state=[
            "pi0",
            "gamma",
            "pi0",
        ],
        allowed_intermediate_particles=["f(0)(980)"],
        allowed_interaction_types=["strong", "EM"],
    )
    assert len(reaction.final_state) == 3

First failing commit is abd875d. Probably fixed best through #144.

Note: the test does not fail anymore after #156

[redeboer]

Another example (with pip install qrules==0.9.7):

import graphviz
import qrules

reaction = qrules.generate_transitions(
    initial_state=("J/psi(1S)", [-1, +1]),
    final_state=["gamma", "pi0", "pi0"],
    allowed_intermediate_particles=["omega(782)"],
    allowed_interaction_types=["strong", "EM"],
    formalism="canonical-helicity",
)
dot = qrules.io.asdot(reaction, collapse_graphs=True)
graphviz.Source(dot)

This seems to be a problem with the DOT rendering though:

>>> reaction.transitions[0].topology
Topology(
  nodes=frozenset({0, 1}),
  edges=FrozenDict({
    -1: Edge(originating_node_id=None, ending_node_id=0),
    3: Edge(originating_node_id=0, ending_node_id=1),
    1: Edge(originating_node_id=1, ending_node_id=None),
    2: Edge(originating_node_id=1, ending_node_id=None),
  }),
)