330 lines
12 KiB
Python
330 lines
12 KiB
Python
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# 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 convienient calculation
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and conversions.
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Authors: Robert Coup, Justin Bronn
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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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__all__ = ['A', 'Area', 'D', 'Distance']
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from decimal import Decimal
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class MeasureBase(object):
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def default_units(self, kwargs):
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"""
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Return the unit value and the 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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for unit, value in kwargs.iteritems():
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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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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 = dict([(k.lower(), v) for k, v in ALIAS.items()])
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def __init__(self, default_unit=None, **kwargs):
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# The base unit is in meters.
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self.m, self._default_unit = self.default_units(kwargs)
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if default_unit and isinstance(default_unit, str):
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self._default_unit = default_unit
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def __getattr__(self, name):
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if name in self.UNITS:
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return self.m / 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 'Distance(%s=%s)' % (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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def __cmp__(self, other):
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if isinstance(other, Distance):
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return cmp(self.m, other.m)
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else:
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return NotImplemented
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def __add__(self, other):
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if isinstance(other, Distance):
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return Distance(default_unit=self._default_unit, m=(self.m + other.m))
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else:
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raise TypeError('Distance must be added with Distance')
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def __iadd__(self, other):
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if isinstance(other, Distance):
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self.m += other.m
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return self
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else:
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raise TypeError('Distance must be added with Distance')
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def __sub__(self, other):
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if isinstance(other, Distance):
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return Distance(default_unit=self._default_unit, m=(self.m - other.m))
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else:
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raise TypeError('Distance must be subtracted from Distance')
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def __isub__(self, other):
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if isinstance(other, Distance):
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self.m -= other.m
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return self
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else:
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raise TypeError('Distance must be subtracted from Distance')
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def __mul__(self, other):
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if isinstance(other, (int, float, long, Decimal)):
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return Distance(default_unit=self._default_unit, m=(self.m * float(other)))
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elif isinstance(other, Distance):
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return Area(default_unit='sq_' + self._default_unit, sq_m=(self.m * other.m))
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else:
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raise TypeError('Distance must be multiplied with number or Distance')
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def __imul__(self, other):
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if isinstance(other, (int, float, long, Decimal)):
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self.m *= float(other)
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return self
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else:
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raise TypeError('Distance must be multiplied with number')
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def __div__(self, other):
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if isinstance(other, (int, float, long, Decimal)):
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return Distance(default_unit=self._default_unit, m=(self.m / float(other)))
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else:
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raise TypeError('Distance must be divided with number')
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def __idiv__(self, other):
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if isinstance(other, (int, float, long, Decimal)):
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self.m /= float(other)
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return self
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else:
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raise TypeError('Distance must be divided with number')
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def __nonzero__(self):
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return bool(self.m)
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class Area(MeasureBase):
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# Getting the square units values and the alias dictionary.
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UNITS = dict([('sq_%s' % k, v ** 2) for k, v in Distance.UNITS.items()])
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ALIAS = dict([(k, 'sq_%s' % v) for k, v in Distance.ALIAS.items()])
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LALIAS = dict([(k.lower(), v) for k, v in ALIAS.items()])
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def __init__(self, default_unit=None, **kwargs):
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self.sq_m, self._default_unit = self.default_units(kwargs)
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if default_unit and isinstance(default_unit, str):
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self._default_unit = default_unit
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def __getattr__(self, name):
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if name in self.UNITS:
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return self.sq_m / self.UNITS[name]
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else:
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raise AttributeError('Unknown unit type: ' + name)
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def __repr__(self):
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return 'Area(%s=%s)' % (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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def __cmp__(self, other):
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if isinstance(other, Area):
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return cmp(self.sq_m, other.sq_m)
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else:
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return NotImplemented
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def __add__(self, other):
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if isinstance(other, Area):
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return Area(default_unit=self._default_unit, sq_m=(self.sq_m + other.sq_m))
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else:
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raise TypeError('Area must be added with Area')
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def __iadd__(self, other):
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if isinstance(other, Area):
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self.sq_m += other.sq_m
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return self
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else:
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raise TypeError('Area must be added with Area')
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def __sub__(self, other):
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if isinstance(other, Area):
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return Area(default_unit=self._default_unit, sq_m=(self.sq_m - other.sq_m))
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else:
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raise TypeError('Area must be subtracted from Area')
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def __isub__(self, other):
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if isinstance(other, Area):
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self.sq_m -= other.sq_m
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return self
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else:
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raise TypeError('Area must be subtracted from Area')
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def __mul__(self, other):
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if isinstance(other, (int, float, long, Decimal)):
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return Area(default_unit=self._default_unit, sq_m=(self.sq_m * float(other)))
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else:
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raise TypeError('Area must be multiplied with number')
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def __imul__(self, other):
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if isinstance(other, (int, float, long, Decimal)):
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self.sq_m *= float(other)
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return self
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else:
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raise TypeError('Area must be multiplied with number')
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def __div__(self, other):
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if isinstance(other, (int, float, long, Decimal)):
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return Area(default_unit=self._default_unit, sq_m=(self.sq_m / float(other)))
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else:
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raise TypeError('Area must be divided with number')
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def __idiv__(self, other):
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if isinstance(other, (int, float, long, Decimal)):
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self.sq_m /= float(other)
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return self
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else:
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raise TypeError('Area must be divided with number')
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def __nonzero__(self):
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return bool(self.sq_m)
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# Shortcuts
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D = Distance
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A = Area
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