Source code for pint.facets.nonmultiplicative.registry


    :copyright: 2022 by Pint Authors, see AUTHORS for more details.
    :license: BSD, see LICENSE for more details.

from __future__ import annotations

from typing import Any, Optional

from ...errors import DimensionalityError, UndefinedUnitError
from ...util import UnitsContainer, logger
from ..plain import PlainRegistry, UnitDefinition
from .definitions import OffsetConverter, ScaleConverter
from .objects import NonMultiplicativeQuantity

[docs]class NonMultiplicativeRegistry(PlainRegistry): """Handle of non multiplicative units (e.g. Temperature). Capabilities: - Register non-multiplicative units and their relations. - Convert between non-multiplicative units. Parameters ---------- default_as_delta : bool If True, non-multiplicative units are interpreted as their *delta* counterparts in multiplications. autoconvert_offset_to_baseunit : bool If True, non-multiplicative units are converted to plain units in multiplications. """ _quantity_class = NonMultiplicativeQuantity def __init__( self, default_as_delta: bool = True, autoconvert_offset_to_baseunit: bool = False, **kwargs: Any, ) -> None: super().__init__(**kwargs) #: When performing a multiplication of units, interpret #: non-multiplicative units as their *delta* counterparts. self.default_as_delta = default_as_delta # Determines if quantities with offset units are converted to their # plain units on multiplication and division. self.autoconvert_offset_to_baseunit = autoconvert_offset_to_baseunit def _parse_units( self, input_string: str, as_delta: Optional[bool] = None, case_sensitive: Optional[bool] = None, ): """ """ if as_delta is None: as_delta = self.default_as_delta return super()._parse_units(input_string, as_delta, case_sensitive) def _add_unit(self, definition: UnitDefinition): super()._add_unit(definition) if definition.is_multiplicative: return if definition.is_logarithmic: return if not isinstance(definition.converter, OffsetConverter): logger.debug( "Cannot autogenerate delta version for a unit in " "which the converter is not an OffsetConverter" ) return delta_name = "delta_" + if definition.symbol: delta_symbol = "Δ" + definition.symbol else: delta_symbol = None delta_aliases = tuple("Δ" + alias for alias in definition.aliases) + tuple( "delta_" + alias for alias in definition.aliases ) delta_reference = self.UnitsContainer( {ref: value for ref, value in definition.reference.items()} ) delta_def = UnitDefinition( delta_name, delta_symbol, delta_aliases, ScaleConverter(definition.converter.scale), delta_reference, ) super()._add_unit(delta_def) def _is_multiplicative(self, u) -> bool: if u in self._units: return self._units[u].is_multiplicative # If the unit is not in the registry might be because it is not # registered with its prefixed version. # TODO: Might be better to register them. names = self.parse_unit_name(u) assert len(names) == 1 _, base_name, _ = names[0] try: return self._units[base_name].is_multiplicative except KeyError: raise UndefinedUnitError(u) def _validate_and_extract(self, units): # u is for unit, e is for exponent nonmult_units = [ (u, e) for u, e in units.items() if not self._is_multiplicative(u) ] # Let's validate source offset units if len(nonmult_units) > 1: # More than one src offset unit is not allowed raise ValueError("more than one offset unit.") elif len(nonmult_units) == 1: # A single src offset unit is present. Extract it # But check that: # - the exponent is 1 # - is not used in multiplicative context nonmult_unit, exponent = nonmult_units.pop() if exponent != 1: raise ValueError("offset units in higher order.") if len(units) > 1 and not self.autoconvert_offset_to_baseunit: raise ValueError("offset unit used in multiplicative context.") return nonmult_unit return None def _add_ref_of_log_or_offset_unit(self, offset_unit, all_units): slct_unit = self._units[offset_unit] if slct_unit.is_logarithmic or (not slct_unit.is_multiplicative): # Extract reference unit slct_ref = slct_unit.reference # If reference unit is not dimensionless if slct_ref != UnitsContainer(): # Extract reference unit (u, e) = [(u, e) for u, e in slct_ref.items()].pop() # Add it back to the unit list return all_units.add(u, e) # Otherwise, return the units unmodified return all_units def _convert(self, value, src, dst, inplace=False): """Convert value from some source to destination units. In addition to what is done by the PlainRegistry, converts between non-multiplicative units. Parameters ---------- value : value src : UnitsContainer source units. dst : UnitsContainer destination units. inplace : (Default value = False) Returns ------- type converted value """ # Conversion needs to consider if non-multiplicative (AKA offset # units) are involved. Conversion is only possible if src and dst # have at most one offset unit per dimension. Other rules are applied # by validate and extract. try: src_offset_unit = self._validate_and_extract(src) except ValueError as ex: raise DimensionalityError(src, dst, extra_msg=f" - In source units, {ex}") try: dst_offset_unit = self._validate_and_extract(dst) except ValueError as ex: raise DimensionalityError( src, dst, extra_msg=f" - In destination units, {ex}" ) if not (src_offset_unit or dst_offset_unit): return super()._convert(value, src, dst, inplace) src_dim = self._get_dimensionality(src) dst_dim = self._get_dimensionality(dst) # If the source and destination dimensionality are different, # then the conversion cannot be performed. if src_dim != dst_dim: raise DimensionalityError(src, dst, src_dim, dst_dim) # clean src from offset units by converting to reference if src_offset_unit: value = self._units[src_offset_unit].converter.to_reference(value, inplace) src = src.remove([src_offset_unit]) # Add reference unit for multiplicative section src = self._add_ref_of_log_or_offset_unit(src_offset_unit, src) # clean dst units from offset units if dst_offset_unit: dst = dst.remove([dst_offset_unit]) # Add reference unit for multiplicative section dst = self._add_ref_of_log_or_offset_unit(dst_offset_unit, dst) # Convert non multiplicative units to the dst. value = super()._convert(value, src, dst, inplace, False) # Finally convert to offset units specified in destination if dst_offset_unit: value = self._units[dst_offset_unit].converter.from_reference( value, inplace ) return value