openstack/deb-python-pint
Code Issues Proposed changes

rewrite get_dimensionality with compact recursion for performance

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This commit is contained in:
Joel B. Mohler
2014-07-01 15:27:02 -04:00
parent 46b8f472ff
commit c8ae9eeccd
1 changed files with 19 additions and 15 deletions
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34
pint/unit.py
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@@ -885,9 +885,8 @@ class UnitRegistry(object):
:param input_units:
:return: dimensionality
"""
dims = UnitsContainer()
if not input_units:
return dims
return UnitsContainer()
if isinstance(input_units, string_types):
input_units = ParserHelper.from_string(input_units)
@@ -895,25 +894,30 @@ class UnitRegistry(object):
if input_units in self._dimensionality_cache:
return copy.copy(self._dimensionality_cache[input_units])
for key, value in input_units.items():
if _is_dim(key):
reg = self._dimensions[key]
if reg.is_base:
dims.add(key, value)
else:
dims *= self.get_dimensionality(reg.reference) ** value
else:
reg = self._units[self.get_name(key)]
if reg.is_base:
dims *= reg.reference ** value
else:
dims *= self.get_dimensionality(reg.reference) ** value
accumulator = defaultdict(lambda: 0.0)
self._get_dimensionality_recurse(input_units, 1.0, accumulator)
dims = UnitsContainer(dict((k, v) for k, v in accumulator.items() if v != 0.))
if '[]' in dims:
del dims['[]']
return dims
def _get_dimensionality_recurse(self, ref, exp, accumulator):
for key, value in ref.items():
exp2 = exp*value
if _is_dim(key):
reg = self._dimensions[key]
if reg.is_base:
accumulator[key] += exp2
elif reg.reference != None:
self._get_dimensionality_recurse(reg.reference, exp2, accumulator)
else:
reg = self._units[self.get_name(key)]
if reg.reference != None:
self._get_dimensionality_recurse(reg.reference, exp2, accumulator)
def get_base_units(self, input_units, check_nonmult=True):
"""Convert unit or dict of units to the base units.