/
__init__.py
70 lines (59 loc) · 2.43 KB
/
__init__.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
"wraps pint in gpkit monomials"
import os
try:
from pint import UnitRegistry, DimensionalityError
ureg = UnitRegistry() # pylint: disable=invalid-name
ureg.load_definitions(os.sep.join([os.path.dirname(__file__),
"usd_cpi.txt"]))
Quantity = ureg.Quantity
except ImportError: # pint is not installed; provide dummy imports
ureg = None # pylint: disable=invalid-name
Quantity = lambda a, b: None
DimensionalityError = None
QTY_CACHE = {}
def qty(unit):
"Returns a Quantity, caching the result for future retrievals"
if unit not in QTY_CACHE:
QTY_CACHE[unit] = Quantity(1, unit)
return QTY_CACHE[unit]
class GPkitUnits(object):
"Return Monomials instead of Quantitites"
division_cache = {}
multiplication_cache = {}
monomial_cache = {}
def __call__(self, arg):
"Returns a unit Monomial, caching the result for future retrievals"
from .. import Monomial
if arg not in self.monomial_cache:
self.monomial_cache[arg] = Monomial(qty(arg))
return self.monomial_cache[arg]
def __getattr__(self, attr):
"Turns an attribute get into a function call"
return self(attr)
def of_division(self, numerator, denominator):
"Cached unit division. Requires Quantity inputs."
if numerator.units is denominator.units:
return 1
key = (id(numerator.units), id(denominator.units))
if key not in self.division_cache:
if numerator.units and denominator.units:
conversion = numerator.units/denominator.units
else:
conversion = numerator.units or 1/denominator.units
try:
self.division_cache[key] = float(conversion)
except DimensionalityError:
raise DimensionalityError(numerator, denominator)
return self.division_cache[key]
def of_product(self, thing1, thing2):
"Cached unit division. Requires united inputs."
# TODO: qty shouldn't be necessary below
mul_units = qty((thing1*thing2).units)
key = id(mul_units)
if key not in self.multiplication_cache:
try:
self.multiplication_cache[key] = (None, float(mul_units))
except DimensionalityError:
self.multiplication_cache[key] = (mul_units, None)
return self.multiplication_cache[key]
units = GPkitUnits()