__all__ = [
'Unit',
'person_units',
'day_units',
'per_day_units',
'dimensionless_units',
'per_day_per_person_units',
'UNIT_SYMBOLS'
]
import os
from typing import Dict, Any
import sympy
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()
[docs]class Unit:
"""A unit of measurement.
Attributes
----------
expression : sympy.Expr
The expression for the unit.
"""
def __init__(self, expression: sympy.Expr):
self.expression = expression
@classmethod
def from_json(cls, data: Dict[str, Any]) -> "Unit":
from mira.sources.util import get_sympy
new_data = data.copy()
new_data["expression"] = get_sympy(data, local_dict=UNIT_SYMBOLS)
assert (new_data.get('expression') is None or
not isinstance(new_data.get('expression'), str))
return cls(new_data["expression"])
def to_json(self) -> dict:
return {"expression": str(self.expression)}
def __repr__(self):
return f"Unit({self.expression})"
person_units = Unit(sympy.Symbol('person'))
day_units = Unit(sympy.Symbol('day'))
per_day_units = Unit(1/sympy.Symbol('day'))
dimensionless_units = Unit(sympy.Integer('1'))
per_day_per_person_units = Unit(1/(sympy.Symbol('day')*sympy.Symbol('person')))