Spin off units and utils

mira/metamodel/units.py

@@ -0,0 +1,51 @@
+__all__ = [
+ 'Unit',
+ 'person_units',
+ 'day_units',
+ 'per_day_units',
+ 'dimensionless_units',
+ 'per_day_per_person_units',
+ 'UNIT_SYMBOLS'
+]
+
+import os
+import sympy
+from pydantic import BaseModel, Field
+from .utils import SympyExprStr
+
+
+class Unit(BaseModel):
+ """A unit of measurement."""
+ class Config:
+ arbitrary_types_allowed = True
+ json_encoders = {
+ SympyExprStr: lambda e: str(e),
+ }
+ json_decoders = {
+ SympyExprStr: lambda e: sympy.parse_expr(e)
+ }
+
+ expression: SympyExprStr = Field(
+ description="The expression for the unit."
+ )
+
+
+person_units = Unit(expression=sympy.Symbol('person'))
+day_units = Unit(expression=sympy.Symbol('day'))
+per_day_units = Unit(expression=1/sympy.Symbol('day'))
+dimensionless_units = Unit(expression=sympy.Integer('1'))
+per_day_per_person_units = Unit(expression=1/(sympy.Symbol('day')*sympy.Symbol('person')))
+
+
+def load_units():
+ path = os.path.join(os.path.dirname(os.path.abspath(__file__)),
+ os.pardir, 'dkg', 'resources', 'unit_names.tsv')
+ with open(path, 'r') as fh:
+ units = {}
+ for line in fh.readlines():
+ symbol = line.strip()
+ units[symbol] = sympy.Symbol(symbol)
+ return units
+
+
+UNIT_SYMBOLS = load_units()

mira/metamodel/utils.py

@@ -0,0 +1,25 @@
+__all__ = ["SympyExprStr"]
+
+import sympy
+
+
+class SympyExprStr(sympy.Expr):
+ @classmethod
+ def __get_validators__(cls):
+ yield cls.validate
+
+ @classmethod
+ def validate(cls, v):
+ if isinstance(v, cls):
+ return v
+ return cls(v)
+
+ @classmethod
+ def __modify_schema__(cls, field_schema):
+ field_schema.update(type="string", example="2*x")
+
+ def __str__(self):
+ return super().__str__()[len(self.__class__.__name__)+1:-1]
+
+ def __repr__(self):
+ return str(self)