QuantityKinds

pint/default_en.txt

@@ -122,13 +122,15 @@ count = []
 
 @import constants_en.txt
 
-
 #### UNITS ####
 # Common and less common, grouped by quantity.
 # Conversion factors are exact (except when noted),
 # although floating-point conversion may introduce inaccuracies
 
 # Angle
+[arc_length] = [length]
+[radius] = [length]
+[angle] = [arc_length] / [radius]
 turn = 2 * π * radian = _ = revolution = cycle = circle
 degree = π / 180 * radian = deg = arcdeg = arcdegree = angular_degree
 arcminute = degree / 60 = arcmin = arc_minute = angular_minute
@@ -212,6 +214,9 @@ degree_Reaumur = 4 / 5 * kelvin; offset: 273.15 = °Re = reaumur = degRe = degre
 atomic_unit_of_temperature = E_h / k = a_u_temp
 planck_temperature = (hbar * c ** 5 / gravitational_constant / k ** 2) ** 0.5
 
+# Specific heat capacity
+# [specific_heat_capacity] = [energy] / [temperature] / [mass] = J / kg / K
+
 # Area
 [area] = [length] ** 2
 are = 100 * meter ** 2
@@ -229,6 +234,7 @@ stere = meter ** 3
 # Frequency
 [frequency] = 1 / [time]
 hertz = 1 / second = Hz
+[angular_frequency] = [angle] / [time]
 revolutions_per_minute = revolution / minute = rpm
 revolutions_per_second = revolution / second = rps
 counts_per_second = count / second = cps
@@ -256,7 +262,7 @@ sverdrup = 1e6 * meter ** 3 / second = sv
 galileo = centimeter / second ** 2 = Gal
 
 # Force
-[force] = [mass] * [acceleration]
+[force] = [mass] * [acceleration] = N
 newton = kilogram * meter / second ** 2 = N
 dyne = gram * centimeter / second ** 2 = dyn
 force_kilogram = g_0 * kilogram = kgf = kilogram_force = pond
@@ -265,7 +271,7 @@ force_metric_ton = g_0 * metric_ton = tf = metric_ton_force = force_t = t_force
 atomic_unit_of_force = E_h / a_0 = a_u_force
 
 # Energy
-[energy] = [force] * [length]
+[energy] = [force] * [length] = J
 joule = newton * meter = J
 erg = dyne * centimeter
 watt_hour = watt * hour = Wh = watthour
@@ -285,8 +291,13 @@ ton_TNT = 1e9 * calorie = tTNT
 tonne_of_oil_equivalent = 1e10 * international_calorie = toe
 atmosphere_liter = atmosphere * liter = atm_l
 
+# Torque
+[moment_arm] = [length] = m
+[torque] = [force] * [moment_arm] = N m
+foot_pound = foot * force_pound = ft_lb = footpound
+
 # Power
-[power] = [energy] / [time]
+[power] = [energy] / [time] = [torque] * [angular_frequency] = [volumetric_flow_rate] * [pressure] = W
 watt = joule / second = W
 volt_ampere = volt * ampere = VA
 horsepower = 550 * foot * force_pound / second = hp = UK_horsepower = hydraulic_horsepower
@@ -299,7 +310,7 @@ standard_liter_per_minute = atmosphere * liter / minute = slpm = slm
 conventional_watt_90 = K_J90 ** 2 * R_K90 / (K_J ** 2 * R_K) * watt = W_90
 
 # Momentum
-[momentum] = [length] * [mass] / [time]
+[momentum] = [velocity] * [mass]
 
 # Density (as auxiliary for pressure)
 [density] = [mass] / [volume]
@@ -328,9 +339,6 @@ foot_H2O = foot * water * g_0 = ftH2O = feet_H2O
 centimeter_H2O = centimeter * water * g_0 = cmH2O = cm_H2O
 sound_pressure_level = 20e-6 * pascal = SPL
 
-# Torque
-[torque] = [force] * [length]
-foot_pound = foot * force_pound = ft_lb = footpound
 
 # Viscosity
 [viscosity] = [pressure] * [time]

pint/delegates/formatter/full.py

@@ -31,6 +31,7 @@
 
 if TYPE_CHECKING:
     from ...compat import Locale
+    from ...facets.kind import KindKind, QuantityKind
     from ...facets.measurement import Measurement
     from ...facets.plain import (
         MagnitudeT,
@@ -130,6 +131,19 @@ def format_unit(
             unit, uspec, sort_func=sort_func, **babel_kwds
         )
 
+    def format_kind(
+        self,
+        kind: KindKind | Iterable[tuple[str, Any]],
+        uspec: str = "",
+        sort_func: SortFunc | None = None,
+        **babel_kwds: Unpack[BabelKwds],
+    ) -> str:
+        uspec = uspec or self.default_format
+        sort_func = sort_func or self.default_sort_func
+        return self.get_formatter(uspec).format_kind(
+            kind, uspec, sort_func=sort_func, **babel_kwds
+        )
+
     def format_quantity(
         self,
         quantity: PlainQuantity[MagnitudeT],
@@ -167,6 +181,19 @@ def format_quantity(
             locale=locale,
         )
 
+    def format_quantitykind(
+        self,
+        quantitykind: QuantityKind | Iterable[tuple[str, Any]],
+        uspec: str = "",
+        sort_func: SortFunc | None = None,
+        **babel_kwds: Unpack[BabelKwds],
+    ) -> str:
+        uspec = uspec or self.default_format
+        sort_func = sort_func or self.default_sort_func
+        return self.get_formatter(uspec).format_quantitykind(
+            quantitykind, uspec, sort_func=sort_func, **babel_kwds
+        )
+
     def format_measurement(
         self,
         measurement: Measurement,

pint/delegates/formatter/plain.py

@@ -39,6 +39,7 @@
 )
 
 if TYPE_CHECKING:
+    from ...facets.kind import KindKind, QuantityKind
     from ...facets.measurement import Measurement
     from ...facets.plain import MagnitudeT, PlainQuantity, PlainUnit
     from ...registry import UnitRegistry
@@ -51,6 +52,41 @@ class BaseFormatter:
     def __init__(self, registry: UnitRegistry | None = None):
         self._registry = registry
 
+    def format_kind(
+        self,
+        kind: KindKind | Iterable[tuple[str, Any]],
+        uspec: str = "",
+        sort_func: SortFunc | None = None,
+        **babel_kwds: Unpack[BabelKwds],
+    ) -> str:
+        """Format a unit (can be compound) into string
+        given a string formatting specification and locale related arguments.
+        """
+        kind = kind._kinds
+        return self.format_unit(kind, uspec, sort_func, **babel_kwds)
+
+    def format_quantitykind(
+        self,
+        quantitykind: QuantityKind,
+        qspec: str = "",
+        sort_func: SortFunc | None = None,
+        **babel_kwds: Unpack[BabelKwds],
+    ) -> str:
+        """Format a quantitykind into string
+        given a string formatting specification and locale related arguments.
+        """
+        quantity = quantitykind.quantity
+
+        registry = self._registry
+
+        mspec, uspec = split_format(
+            qspec, registry.formatter.default_format, registry.separate_format_defaults
+        )
+
+        mu = self.format_quantity(quantity, qspec, sort_func, **babel_kwds)
+        k = self.format_kind(quantitykind.kinds, uspec, sort_func, **babel_kwds)
+        return mu + " " + k
+
 
 class DefaultFormatter(BaseFormatter):
     """Simple, localizable plain text formatter.

pint/delegates/txt_defparser/plain.py

@@ -221,11 +221,11 @@ class DerivedDimensionDefinition(
 ):
     """Definition of a derived dimension::
 
-        [dimension name] = <relation to other dimensions>
+        [dimension name] = <relation to other dimensions> [= <preferred unit>]
 
     Example::
 
-        [density] = [mass] / [volume]
+        [density] = [mass] / [volume] = kilogram / meter ** 3
     """
 
     @classmethod
@@ -235,23 +235,31 @@ def from_string_and_config(
         if not (s.startswith("[") and "=" in s):
             return None
 
-        name, value, *aliases = s.split("=")
+        name, value, *alt_refs = (p.strip() for p in s.split("="))
 
-        if aliases:
-            return common.DefinitionSyntaxError(
-                "Derived dimensions cannot have aliases."
-            )
+        preferred_unit = None
+        if alt_refs:
+            if "[" not in alt_refs[-1]:
+                preferred_unit = alt_refs[-1]
+                alt_refs = alt_refs[:-1]
+        else:
+            alt_refs = []
 
-        try:
-            reference = config.to_dimension_container(value)
-        except common.DefinitionSyntaxError as exc:
-            return common.DefinitionSyntaxError(
-                f"In {name} derived dimensions must only be referenced "
-                f"to dimensions. {exc}"
-            )
+        def to_dim_container(string):
+            try:
+                reference = config.to_dimension_container(string)
+            except common.DefinitionSyntaxError as exc:
+                return common.DefinitionSyntaxError(
+                    f"In {name} derived dimensions must only be referenced "
+                    f"to dimensions. {exc}"
+                )
+            return reference
+
+        reference = to_dim_container(value)
+        alternate_references = tuple([to_dim_container(ref) for ref in alt_refs])
 
         try:
-            return cls(name.strip(), reference)
+            return cls(name.strip(), reference, preferred_unit, alternate_references)
         except Exception as exc:
             return common.DefinitionSyntaxError(str(exc))
 

pint/facets/__init__.py

@@ -72,6 +72,7 @@ class that belongs to a registry that has NumpyRegistry as one of its bases.
 from .context import ContextRegistry, GenericContextRegistry
 from .dask import DaskRegistry, GenericDaskRegistry
 from .group import GenericGroupRegistry, GroupRegistry
+from .kind import GenericKindRegistry, KindRegistry
 from .measurement import GenericMeasurementRegistry, MeasurementRegistry
 from .nonmultiplicative import (
     GenericNonMultiplicativeRegistry,
@@ -103,4 +104,6 @@ class that belongs to a registry that has NumpyRegistry as one of its bases.
     "QuantityT",
     "UnitT",
     "MagnitudeT",
+    "GenericKindRegistry",
+    "KindRegistry",
 ]

pint/facets/kind/__init__.py

@@ -0,0 +1,21 @@
+"""
+    pint.facets.Kind
+    ~~~~~~~~~~~~~~~~~~~~~~~
+
+    Adds pint the capability to handle Kinds (quantities with uncertainties).
+
+    :copyright: 2022 by Pint Authors, see AUTHORS for more details.
+    :license: BSD, see LICENSE for more details.
+"""
+
+from __future__ import annotations
+
+from .objects import KindKind, KindQuantity
+from .registry import GenericKindRegistry, KindRegistry
+
+__all__ = [
+    "KindKind",
+    "KindQuantity",
+    "KindRegistry",
+    "GenericKindRegistry",
+]