348 lines
12 KiB
Python
348 lines
12 KiB
Python
# Copyright (c) 2007, Robert Coup <robert.coup@onetrackmind.co.nz>
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without modification,
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# are permitted provided that the following conditions are met:
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#
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# 1. Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# 3. Neither the name of Distance nor the names of its contributors may be used
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# to endorse or promote products derived from this software without
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# specific prior written permission.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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# ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
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# ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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#
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"""
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Distance and Area objects to allow for sensible and convenient calculation
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and conversions.
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Authors: Robert Coup, Justin Bronn, Riccardo Di Virgilio
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Inspired by GeoPy (http://exogen.case.edu/projects/geopy/)
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and Geoff Biggs' PhD work on dimensioned units for robotics.
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"""
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from decimal import Decimal
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from functools import total_ordering
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from django.utils import six
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__all__ = ['A', 'Area', 'D', 'Distance']
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NUMERIC_TYPES = six.integer_types + (float, Decimal)
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AREA_PREFIX = "sq_"
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def pretty_name(obj):
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return obj.__name__ if obj.__class__ == type else obj.__class__.__name__
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@total_ordering
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class MeasureBase(object):
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STANDARD_UNIT = None
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ALIAS = {}
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UNITS = {}
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LALIAS = {}
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def __init__(self, default_unit=None, **kwargs):
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value, self._default_unit = self.default_units(kwargs)
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setattr(self, self.STANDARD_UNIT, value)
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if default_unit and isinstance(default_unit, six.string_types):
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self._default_unit = default_unit
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def _get_standard(self):
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return getattr(self, self.STANDARD_UNIT)
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def _set_standard(self, value):
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setattr(self, self.STANDARD_UNIT, value)
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standard = property(_get_standard, _set_standard)
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def __getattr__(self, name):
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if name in self.UNITS:
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return self.standard / self.UNITS[name]
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else:
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raise AttributeError('Unknown unit type: %s' % name)
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def __repr__(self):
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return '%s(%s=%s)' % (pretty_name(self), self._default_unit, getattr(self, self._default_unit))
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def __str__(self):
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return '%s %s' % (getattr(self, self._default_unit), self._default_unit)
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# **** Comparison methods ****
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def __eq__(self, other):
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if isinstance(other, self.__class__):
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return self.standard == other.standard
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else:
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return NotImplemented
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def __lt__(self, other):
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if isinstance(other, self.__class__):
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return self.standard < other.standard
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else:
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return NotImplemented
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# **** Operators methods ****
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def __add__(self, other):
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if isinstance(other, self.__class__):
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return self.__class__(
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default_unit=self._default_unit,
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**{self.STANDARD_UNIT: (self.standard + other.standard)}
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)
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else:
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raise TypeError('%(class)s must be added with %(class)s' % {"class": pretty_name(self)})
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def __iadd__(self, other):
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if isinstance(other, self.__class__):
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self.standard += other.standard
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return self
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else:
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raise TypeError('%(class)s must be added with %(class)s' % {"class": pretty_name(self)})
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def __sub__(self, other):
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if isinstance(other, self.__class__):
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return self.__class__(
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default_unit=self._default_unit,
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**{self.STANDARD_UNIT: (self.standard - other.standard)}
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)
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else:
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raise TypeError('%(class)s must be subtracted from %(class)s' % {"class": pretty_name(self)})
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def __isub__(self, other):
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if isinstance(other, self.__class__):
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self.standard -= other.standard
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return self
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else:
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raise TypeError('%(class)s must be subtracted from %(class)s' % {"class": pretty_name(self)})
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def __mul__(self, other):
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if isinstance(other, NUMERIC_TYPES):
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return self.__class__(
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default_unit=self._default_unit,
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**{self.STANDARD_UNIT: (self.standard * other)}
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)
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else:
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raise TypeError('%(class)s must be multiplied with number' % {"class": pretty_name(self)})
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def __imul__(self, other):
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if isinstance(other, NUMERIC_TYPES):
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self.standard *= float(other)
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return self
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else:
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raise TypeError('%(class)s must be multiplied with number' % {"class": pretty_name(self)})
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def __rmul__(self, other):
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return self * other
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def __truediv__(self, other):
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if isinstance(other, self.__class__):
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return self.standard / other.standard
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if isinstance(other, NUMERIC_TYPES):
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return self.__class__(
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default_unit=self._default_unit,
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**{self.STANDARD_UNIT: (self.standard / other)}
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)
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else:
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raise TypeError('%(class)s must be divided with number or %(class)s' % {"class": pretty_name(self)})
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def __div__(self, other): # Python 2 compatibility
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return type(self).__truediv__(self, other)
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def __itruediv__(self, other):
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if isinstance(other, NUMERIC_TYPES):
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self.standard /= float(other)
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return self
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else:
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raise TypeError('%(class)s must be divided with number' % {"class": pretty_name(self)})
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def __idiv__(self, other): # Python 2 compatibility
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return type(self).__itruediv__(self, other)
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def __bool__(self):
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return bool(self.standard)
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def __nonzero__(self): # Python 2 compatibility
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return type(self).__bool__(self)
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def default_units(self, kwargs):
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"""
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Return the unit value and the default units specified
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from the given keyword arguments dictionary.
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"""
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val = 0.0
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default_unit = self.STANDARD_UNIT
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for unit, value in six.iteritems(kwargs):
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if not isinstance(value, float):
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value = float(value)
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if unit in self.UNITS:
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val += self.UNITS[unit] * value
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default_unit = unit
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elif unit in self.ALIAS:
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u = self.ALIAS[unit]
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val += self.UNITS[u] * value
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default_unit = u
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else:
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lower = unit.lower()
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if lower in self.UNITS:
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val += self.UNITS[lower] * value
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default_unit = lower
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elif lower in self.LALIAS:
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u = self.LALIAS[lower]
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val += self.UNITS[u] * value
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default_unit = u
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else:
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raise AttributeError('Unknown unit type: %s' % unit)
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return val, default_unit
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@classmethod
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def unit_attname(cls, unit_str):
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"""
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Retrieves the unit attribute name for the given unit string.
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For example, if the given unit string is 'metre', 'm' would be returned.
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An exception is raised if an attribute cannot be found.
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"""
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lower = unit_str.lower()
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if unit_str in cls.UNITS:
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return unit_str
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elif lower in cls.UNITS:
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return lower
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elif lower in cls.LALIAS:
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return cls.LALIAS[lower]
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else:
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raise Exception('Could not find a unit keyword associated with "%s"' % unit_str)
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class Distance(MeasureBase):
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STANDARD_UNIT = "m"
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UNITS = {
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'chain': 20.1168,
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'chain_benoit': 20.116782,
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'chain_sears': 20.1167645,
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'british_chain_benoit': 20.1167824944,
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'british_chain_sears': 20.1167651216,
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'british_chain_sears_truncated': 20.116756,
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'cm': 0.01,
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'british_ft': 0.304799471539,
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'british_yd': 0.914398414616,
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'clarke_ft': 0.3047972654,
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'clarke_link': 0.201166195164,
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'fathom': 1.8288,
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'ft': 0.3048,
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'german_m': 1.0000135965,
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'gold_coast_ft': 0.304799710181508,
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'indian_yd': 0.914398530744,
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'inch': 0.0254,
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'km': 1000.0,
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'link': 0.201168,
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'link_benoit': 0.20116782,
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'link_sears': 0.20116765,
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'm': 1.0,
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'mi': 1609.344,
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'mm': 0.001,
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'nm': 1852.0,
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'nm_uk': 1853.184,
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'rod': 5.0292,
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'sears_yd': 0.91439841,
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'survey_ft': 0.304800609601,
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'um': 0.000001,
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'yd': 0.9144,
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}
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# Unit aliases for `UNIT` terms encountered in Spatial Reference WKT.
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ALIAS = {
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'centimeter': 'cm',
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'foot': 'ft',
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'inches': 'inch',
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'kilometer': 'km',
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'kilometre': 'km',
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'meter': 'm',
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'metre': 'm',
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'micrometer': 'um',
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'micrometre': 'um',
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'millimeter': 'mm',
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'millimetre': 'mm',
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'mile': 'mi',
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'yard': 'yd',
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'British chain (Benoit 1895 B)': 'british_chain_benoit',
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'British chain (Sears 1922)': 'british_chain_sears',
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'British chain (Sears 1922 truncated)': 'british_chain_sears_truncated',
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'British foot (Sears 1922)': 'british_ft',
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'British foot': 'british_ft',
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'British yard (Sears 1922)': 'british_yd',
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'British yard': 'british_yd',
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"Clarke's Foot": 'clarke_ft',
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"Clarke's link": 'clarke_link',
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'Chain (Benoit)': 'chain_benoit',
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'Chain (Sears)': 'chain_sears',
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'Foot (International)': 'ft',
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'German legal metre': 'german_m',
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'Gold Coast foot': 'gold_coast_ft',
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'Indian yard': 'indian_yd',
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'Link (Benoit)': 'link_benoit',
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'Link (Sears)': 'link_sears',
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'Nautical Mile': 'nm',
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'Nautical Mile (UK)': 'nm_uk',
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'US survey foot': 'survey_ft',
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'U.S. Foot': 'survey_ft',
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'Yard (Indian)': 'indian_yd',
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'Yard (Sears)': 'sears_yd'
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}
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LALIAS = {k.lower(): v for k, v in ALIAS.items()}
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def __mul__(self, other):
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if isinstance(other, self.__class__):
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return Area(
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default_unit=AREA_PREFIX + self._default_unit,
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**{AREA_PREFIX + self.STANDARD_UNIT: (self.standard * other.standard)}
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)
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elif isinstance(other, NUMERIC_TYPES):
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return self.__class__(
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default_unit=self._default_unit,
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**{self.STANDARD_UNIT: (self.standard * other)}
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)
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else:
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raise TypeError('%(distance)s must be multiplied with number or %(distance)s' % {
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"distance": pretty_name(self.__class__),
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})
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class Area(MeasureBase):
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STANDARD_UNIT = AREA_PREFIX + Distance.STANDARD_UNIT
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# Getting the square units values and the alias dictionary.
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UNITS = {'%s%s' % (AREA_PREFIX, k): v ** 2 for k, v in Distance.UNITS.items()}
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ALIAS = {k: '%s%s' % (AREA_PREFIX, v) for k, v in Distance.ALIAS.items()}
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LALIAS = {k.lower(): v for k, v in ALIAS.items()}
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def __truediv__(self, other):
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if isinstance(other, NUMERIC_TYPES):
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return self.__class__(
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default_unit=self._default_unit,
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**{self.STANDARD_UNIT: (self.standard / other)}
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)
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else:
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raise TypeError('%(class)s must be divided by a number' % {"class": pretty_name(self)})
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def __div__(self, other): # Python 2 compatibility
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return type(self).__truediv__(self, other)
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# Shortcuts
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D = Distance
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A = Area
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