Adds a currency dimension

docs/usage.rst

@@ -551,6 +551,7 @@ atoms and molecules:
      current_mks: A
      luminous_intensity: cd
      logarithmic: Np
+     currency: $
     Other Units:
      energy: eV
    >>> print(atomic_unit_system)
@@ -575,6 +576,7 @@ It is also legal to define a unit system using :class:`unyt.Unit
       current_mks: A
       luminous_intensity: cd
       logarithmic: Np
+      currency: $
      Other Units:
 
 Or with a quantity:
@@ -590,6 +592,7 @@ Or with a quantity:
       current_mks: A
       luminous_intensity: cd
       logarithmic: Np
+      currency: $
      Other Units:
 
 

unyt/_parsing.py

@@ -89,6 +89,11 @@ def parse_unyt_expr(unit_expr):
     # parser tries to interpret it as the modulo operator
     unit_expr = unit_expr.replace("%", "percent")
     unit_expr = unit_expr.replace("°", "deg")
+    unit_expr = unit_expr.replace("$", "dollars")
+    unit_expr = unit_expr.replace("¢", "cents")
+    unit_expr = unit_expr.replace("\u20ac", "euros")
+    unit_expr = unit_expr.replace("\u00a3", "pounds")
+    unit_expr = unit_expr.replace("\u00a5", "yen")
     try:
         unit_expr = parse_expr(
             unit_expr, global_dict=global_dict, transformations=unit_text_transform

unyt/_physical_ratios.py

@@ -173,3 +173,6 @@
 # IEC 60027-3: https://webstore.iec.ch/publication/94
 # NIST Special Publication 811: https://www.nist.gov/pml/special-publication-811
 neper_per_bel = np.log(10) / 2
+
+# Currency
+dollars_per_cent = 0.01

unyt/_unit_lookup_table.py

@@ -24,6 +24,7 @@
     amu_kg,
     avogadros_number,
     boltzmann_constant_J_per_K,
+    dollars_per_cent,
     elementary_charge_C,
     eps_0,
     jansky_mks,
@@ -89,6 +90,15 @@
         ("A", (1.0, dimensions.current_mks, 0.0, r"\rm{A}", True)),
         ("cd", (1.0, dimensions.luminous_intensity, 0.0, r"\rm{cd}", True)),
         ("mol", (1.0 / amu_grams, dimensions.dimensionless, 0.0, r"\rm{mol}", True)),
+        # some currencies
+        ("$", (1.0, dimensions.currency, 0.0, r"\$", False)),
+        (
+            "¢",
+            (dollars_per_cent, dimensions.currency, 0.0, r"\textcent", False),
+        ),  # ('CENT SIGN' UxA2)
+        ("\u20ac", (1.0, dimensions.currency, 0.0, r"\texteuro", False)),
+        ("\u00a3", (1.0, dimensions.currency, 0.0, r"\textsterling", False)),
+        ("\u00a5", (1.0, dimensions.currency, 0.0, r"\textyen", False)),
         # some cgs
         ("dyn", (1.0e-5, dimensions.force, 0.0, r"\rm{dyn}", True)),
         ("erg", (1.0e-7, dimensions.energy, 0.0, r"\rm{erg}", True)),
@@ -413,6 +423,7 @@
     dimensions.angle: "radian",
     dimensions.current_mks: "A",
     dimensions.luminous_intensity: "cd",
+    dimensions.currency: "$",
 }
 
 physical_constants = OrderedDict(
@@ -505,6 +516,12 @@
         ("A", ("ampere", "amp", "Amp")),
         ("cd", ("candela",)),
         ("mol", ("mole",)),
+        # some currencies
+        ("$", ("dollars", "dollar", "USD", "usd")),
+        ("¢", ("cent", "cents")),
+        ("£", ("pounds", "sterling", "GBP", "gbp")),
+        ("€", ("euros", "euro", "EUR", "eur")),
+        ("¥", ("yen", "Yen", "JPY", "jpy")),
         # some cgs
         ("dyn", ("dyne",)),
         ("erg", ("ergs",)),

unyt/array.py

@@ -152,7 +152,7 @@
 _NUMB_PATTERN = r"^[+/-]?((?:0|[1-9]\d*)(?:\.\d*)?(?:[eE][+\-]?\d+)|\d*\.?\d+|\d+\.?\d*|nan\s|inf\s)"  # noqa: E501
 # *all* greek letters are considered valid unit string elements.
 # This may be an overshoot. We rely on unyt.Unit to do the actual validation
-_UNIT_PATTERN = r"([α-ωΑ-Ωa-zA-Z]+(\*\*([+/-]?[0-9]+)|[*/])?)+"
+_UNIT_PATTERN = r"([α-ωΑ-Ωa-zA-Z$¢¥€£]+(\*\*([+/-]?[0-9]+)|[*/])?)+"
 _QUAN_PATTERN = r"{}\s*{}".format(_NUMB_PATTERN, _UNIT_PATTERN)
 _NUMB_REGEXP = re.compile(_NUMB_PATTERN)
 _UNIT_REGEXP = re.compile(_UNIT_PATTERN)

unyt/dimensions.py

@@ -36,6 +36,9 @@
 dimensionless = sympify(1)
 #: logarithmic
 logarithmic = Symbol("(logarithmic)", positive=True)
+#: currency
+currency = Symbol("(currency)", positive=True)
+
 
 #: A list of all of the base dimensions
 base_dimensions = [
@@ -48,6 +51,7 @@
     dimensionless,
     luminous_intensity,
     logarithmic,
+    currency,
 ]
 
 #
@@ -152,6 +156,19 @@
 #: inductance
 inductance = inductance_mks = magnetic_flux_mks / current_mks
 
+# Cost basis units
+#: cost per length
+cost_per_length = cost_per_distance = currency / length
+#: cost per area
+cost_per_area = currency / area
+#: cost per volume
+cost_per_volume = currency / volume
+#: cost per energy
+cost_per_energy = cost_per_erg = currency / energy
+#: cost per power
+cost_per_power = currency / power
+
+
 #: a list containing all derived_dimensions
 derived_dimensions = [
     rate,
@@ -187,6 +204,13 @@
     luminance,
     spatial_frequency,
     angular_frequency,
+    cost_per_distance,
+    cost_per_length,
+    cost_per_area,
+    cost_per_volume,
+    cost_per_energy,
+    cost_per_erg,
+    cost_per_power,
 ]
 
 

unyt/unit_object.py

@@ -341,6 +341,8 @@ def __str__(self):
             return "°F"
         if unit_str == "delta_degF":
             return "Δ°F"
+        if unit_str == "dollars":
+            return "$"
         # @todo: don't use dunder method?
         return unit_str
 

unyt/unit_systems.py

@@ -184,6 +184,9 @@ class UnitSystem:
     luminous_intensity_unit : string or :class:`unyt.unit_object.Unit`, optional
         The base luminous intensity unit of this unit system.
         Defaults to "cd".
+    currency_unit : string or :class:`unyt.unit_object.Unit`, optional
+        The base currency unit for this unit system.
+        Defaults to "$".
     registry : :class:`unyt.unit_registry.UnitRegistry` object
         The unit registry associated with this unit system. Only
         useful for defining unit systems based on code units.
@@ -200,6 +203,7 @@ def __init__(
         current_mks_unit="A",
         luminous_intensity_unit="cd",
         logarithmic_unit="Np",
+        currency_unit="$",
         registry=None,
     ):
         self.registry = registry
@@ -213,6 +217,7 @@ def __init__(
                 (dimensions.current_mks, current_mks_unit),
                 (dimensions.luminous_intensity, luminous_intensity_unit),
                 (dimensions.logarithmic, logarithmic_unit),
+                (dimensions.currency, currency_unit),
             ]
         )
         for k, v in self.units_map.items():
@@ -246,6 +251,7 @@ def __init__(
             "current_mks",
             "luminous_intensity",
             "logarithmic",
+            "currency",
         ]
         self.registry = registry
         self.base_units = self.units_map.copy()
@@ -298,7 +304,9 @@ def has_current_mks(self):
 
 
 #: The CGS unit system
-cgs_unit_system = UnitSystem("cgs", "cm", "g", "s", current_mks_unit=None)
+cgs_unit_system = UnitSystem(
+    "cgs", "cm", "g", "s", currency_unit="$", current_mks_unit=None
+)
 cgs_unit_system["energy"] = "erg"
 cgs_unit_system["specific_energy"] = "erg/g"
 cgs_unit_system["pressure"] = "dyne/cm**2"
@@ -309,7 +317,7 @@ def has_current_mks(self):
 cgs_unit_system["power"] = "erg/s"
 
 #: The MKS unit system
-mks_unit_system = UnitSystem("mks", "m", "kg", "s")
+mks_unit_system = UnitSystem("mks", "m", "kg", "s", currency_unit="$")
 mks_unit_system["energy"] = "J"
 mks_unit_system["specific_energy"] = "J/kg"
 mks_unit_system["pressure"] = "Pa"
@@ -326,7 +334,9 @@ def has_current_mks(self):
 mks_unit_system["luminous_flux"] = "lm"
 
 #: The imperial unit system
-imperial_unit_system = UnitSystem("imperial", "ft", "lb", "s", temperature_unit="R")
+imperial_unit_system = UnitSystem(
+    "imperial", "ft", "lb", "s", temperature_unit="R", currency_unit="$"
+)
 imperial_unit_system["force"] = "lbf"
 imperial_unit_system["energy"] = "ft*lbf"
 imperial_unit_system["pressure"] = "lbf/ft**2"