MAINT: simplify Fraction construction and notation

src/qrules/__init__.py

@@ -79,7 +79,7 @@ def check_reaction_violations(  # noqa: C901, PLR0917
     mass_conservation_factor: float | None = 3.0,
     particle_db: ParticleCollection | None = None,
     max_angular_momentum: int = 1,
-    max_spin_magnitude: float | Fraction = Fraction(2, 1),
+    max_spin_magnitude: float | Fraction = 2,
 ) -> set[frozenset[str]]:
     """Determine violated interaction rules for a given particle reaction.
 
@@ -213,7 +213,7 @@ def check_edge_qn_conservation() -> set[frozenset[str]]:
         InteractionProperties(l_magnitude=l_magnitude, s_magnitude=s_magnitude)
         for l_magnitude, s_magnitude in product(
             _int_domain(0, max_angular_momentum),
-            _halves_domain(Fraction(0, 1), Fraction(max_spin_magnitude)),
+            _halves_domain(Fraction(0), Fraction(max_spin_magnitude)),
         )
     ]
 
@@ -278,7 +278,7 @@ def generate_transitions(  # noqa: PLR0917
     particle_db: ParticleCollection | None = None,
     mass_conservation_factor: float | None = 3.0,
     max_angular_momentum: int = 2,
-    max_spin_magnitude: float | Fraction = Fraction(2, 1),
+    max_spin_magnitude: float | Fraction = 2,
     topology_building: str = "isobar",
     number_of_threads: int | None = None,
 ) -> ReactionInfo:
@@ -366,7 +366,7 @@ def generate_transitions(  # noqa: PLR0917
         formalism=formalism,
         mass_conservation_factor=mass_conservation_factor,
         max_angular_momentum=max_angular_momentum,
-        max_spin_magnitude=Fraction(max_spin_magnitude),
+        max_spin_magnitude=max_spin_magnitude,
         topology_building=topology_building,
         number_of_threads=number_of_threads,
     )

src/qrules/combinatorics.py

@@ -234,8 +234,8 @@ def fill_spin_projections(state: StateDefinition) -> StateWithSpins:
             particle_name = state
             particle = particle_db[particle_name]
             spin_projections = set(arange(-particle.spin, particle.spin + 1))
-            if particle.mass == 0.0 and Fraction(0, 1) in spin_projections:
-                spin_projections.remove(Fraction(0, 1))
+            if particle.mass == 0.0 and Fraction(0) in spin_projections:
+                spin_projections.remove(Fraction(0))
             return particle_name, sorted(spin_projections)
         return state
 

src/qrules/conservation_rules.py

@@ -855,7 +855,7 @@ def calculate_hypercharge(
         or edge_qns.tau_lepton_number
     ):
         return True
-    isospin_3 = Fraction(0, 1)
+    isospin_3 = Fraction(0)
     if edge_qns.isospin_projection:
         isospin_3 = edge_qns.isospin_projection
     return float(edge_qns.charge) == isospin_3 + 0.5 * calculate_hypercharge(edge_qns)

src/qrules/particle.py

@@ -56,11 +56,11 @@ def _validate_fraction_for_spin(
     attribute: Attribute,  # noqa: ARG001
     value: Fraction,  # noqa: ARG001
 ) -> Any:
-    if instance.magnitude % Fraction(1, 2) != Fraction(0, 1):
+    if instance.magnitude % Fraction(1, 2) != Fraction(0):
         msg = f"Spin magnitude {instance.magnitude} has to be a multitude of 0.5"
         raise ValueError(msg)
     if abs(instance.projection) > instance.magnitude:
-        if instance.magnitude < Fraction(0, 1):
+        if instance.magnitude < Fraction(0):
             msg = f"Spin magnitude has to be positive, but is {instance.magnitude}"
             raise ValueError(msg)
         msg = (

src/qrules/quantum_numbers.py

@@ -234,7 +234,7 @@ class InteractionProperties:
 
 
 def arange(
-    x_1: Fraction, x_2: Fraction, delta: Fraction = Fraction(1, 1)
+    x_1: Fraction, x_2: Fraction, delta: Fraction = Fraction(1)
 ) -> Generator[Fraction, None, None]:
     current = Fraction(x_1)
     delta = Fraction(delta)

src/qrules/settings.py

@@ -127,7 +127,7 @@ def create_interaction_settings(  # noqa: PLR0917
     nbody_topology: bool = False,
     mass_conservation_factor: float | None = 3.0,
     max_angular_momentum: int = 2,
-    max_spin_magnitude: float | Fraction = Fraction(2, 1),
+    max_spin_magnitude: float | Fraction = 2,
 ) -> dict[InteractionType, tuple[EdgeSettings, NodeSettings]]:
     """Create a container that holds the settings for `.InteractionType`."""
     formalism_edge_settings = EdgeSettings(
@@ -246,8 +246,8 @@ def __get_spin_magnitudes(
     is_nbody: bool, max_spin_magnitude: Fraction
 ) -> list[Fraction]:
     if is_nbody:
-        return [Fraction(0, 1)]
-    return _halves_domain(Fraction(0, 1), max_spin_magnitude)
+        return [Fraction(0)]
+    return _halves_domain(Fraction(0), max_spin_magnitude)
 
 
 def _create_domains(particle_db: ParticleCollection) -> dict[Any, list]:
@@ -308,7 +308,7 @@ def __positive_halves_domain(
     particle_db: ParticleCollection, attr_getter: Callable[[Particle], Any]
 ) -> list[Fraction]:
     values = set(map(attr_getter, particle_db))
-    return _halves_domain(Fraction(0, 1), max(values))
+    return _halves_domain(Fraction(0), max(values))
 
 
 def __positive_int_domain(

src/qrules/transition.py

@@ -245,7 +245,7 @@ def __init__(  # noqa: C901, PLR0912, PLR0917
         reload_pdg: bool = False,
         mass_conservation_factor: float | None = 3.0,
         max_angular_momentum: int = 1,
-        max_spin_magnitude: float | Fraction = Fraction(2, 1),
+        max_spin_magnitude: float | Fraction = 2,
         number_of_threads: int | None = None,
     ) -> None:
         if number_of_threads is not None: