/django/contrib/gis/measure.py
https://code.google.com/p/mango-py/ · Python · 336 lines · 300 code · 0 blank · 36 comment · 15 complexity · fc0142a37292eb9c41893aabb9a7b12f MD5 · raw file
- # Copyright (c) 2007, Robert Coup <robert.coup@onetrackmind.co.nz>
- # All rights reserved.
- #
- # Redistribution and use in source and binary forms, with or without modification,
- # are permitted provided that the following conditions are met:
- #
- # 1. Redistributions of source code must retain the above copyright notice,
- # this list of conditions and the following disclaimer.
- #
- # 2. Redistributions in binary form must reproduce the above copyright
- # notice, this list of conditions and the following disclaimer in the
- # documentation and/or other materials provided with the distribution.
- #
- # 3. Neither the name of Distance nor the names of its contributors may be used
- # to endorse or promote products derived from this software without
- # specific prior written permission.
- #
- # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
- # ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- # WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- # DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
- # ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
- # (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
- # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
- # ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
- # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- # SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- #
- """
- Distance and Area objects to allow for sensible and convienient calculation
- and conversions.
- Authors: Robert Coup, Justin Bronn
- Inspired by GeoPy (http://exogen.case.edu/projects/geopy/)
- and Geoff Biggs' PhD work on dimensioned units for robotics.
- """
- __all__ = ['A', 'Area', 'D', 'Distance']
- from decimal import Decimal
- class MeasureBase(object):
- def default_units(self, kwargs):
- """
- Return the unit value and the default units specified
- from the given keyword arguments dictionary.
- """
- val = 0.0
- for unit, value in kwargs.iteritems():
- if not isinstance(value, float): value = float(value)
- if unit in self.UNITS:
- val += self.UNITS[unit] * value
- default_unit = unit
- elif unit in self.ALIAS:
- u = self.ALIAS[unit]
- val += self.UNITS[u] * value
- default_unit = u
- else:
- lower = unit.lower()
- if lower in self.UNITS:
- val += self.UNITS[lower] * value
- default_unit = lower
- elif lower in self.LALIAS:
- u = self.LALIAS[lower]
- val += self.UNITS[u] * value
- default_unit = u
- else:
- raise AttributeError('Unknown unit type: %s' % unit)
- return val, default_unit
- @classmethod
- def unit_attname(cls, unit_str):
- """
- Retrieves the unit attribute name for the given unit string.
- For example, if the given unit string is 'metre', 'm' would be returned.
- An exception is raised if an attribute cannot be found.
- """
- lower = unit_str.lower()
- if unit_str in cls.UNITS:
- return unit_str
- elif lower in cls.UNITS:
- return lower
- elif lower in cls.LALIAS:
- return cls.LALIAS[lower]
- else:
- raise Exception('Could not find a unit keyword associated with "%s"' % unit_str)
- class Distance(MeasureBase):
- UNITS = {
- 'chain' : 20.1168,
- 'chain_benoit' : 20.116782,
- 'chain_sears' : 20.1167645,
- 'british_chain_benoit' : 20.1167824944,
- 'british_chain_sears' : 20.1167651216,
- 'british_chain_sears_truncated' : 20.116756,
- 'cm' : 0.01,
- 'british_ft' : 0.304799471539,
- 'british_yd' : 0.914398414616,
- 'clarke_ft' : 0.3047972654,
- 'clarke_link' : 0.201166195164,
- 'fathom' : 1.8288,
- 'ft': 0.3048,
- 'german_m' : 1.0000135965,
- 'gold_coast_ft' : 0.304799710181508,
- 'indian_yd' : 0.914398530744,
- 'inch' : 0.0254,
- 'km': 1000.0,
- 'link' : 0.201168,
- 'link_benoit' : 0.20116782,
- 'link_sears' : 0.20116765,
- 'm': 1.0,
- 'mi': 1609.344,
- 'mm' : 0.001,
- 'nm': 1852.0,
- 'nm_uk' : 1853.184,
- 'rod' : 5.0292,
- 'sears_yd' : 0.91439841,
- 'survey_ft' : 0.304800609601,
- 'um' : 0.000001,
- 'yd': 0.9144,
- }
- # Unit aliases for `UNIT` terms encountered in Spatial Reference WKT.
- ALIAS = {
- 'centimeter' : 'cm',
- 'foot' : 'ft',
- 'inches' : 'inch',
- 'kilometer' : 'km',
- 'kilometre' : 'km',
- 'meter' : 'm',
- 'metre' : 'm',
- 'micrometer' : 'um',
- 'micrometre' : 'um',
- 'millimeter' : 'mm',
- 'millimetre' : 'mm',
- 'mile' : 'mi',
- 'yard' : 'yd',
- 'British chain (Benoit 1895 B)' : 'british_chain_benoit',
- 'British chain (Sears 1922)' : 'british_chain_sears',
- 'British chain (Sears 1922 truncated)' : 'british_chain_sears_truncated',
- 'British foot (Sears 1922)' : 'british_ft',
- 'British foot' : 'british_ft',
- 'British yard (Sears 1922)' : 'british_yd',
- 'British yard' : 'british_yd',
- "Clarke's Foot" : 'clarke_ft',
- "Clarke's link" : 'clarke_link',
- 'Chain (Benoit)' : 'chain_benoit',
- 'Chain (Sears)' : 'chain_sears',
- 'Foot (International)' : 'ft',
- 'German legal metre' : 'german_m',
- 'Gold Coast foot' : 'gold_coast_ft',
- 'Indian yard' : 'indian_yd',
- 'Link (Benoit)': 'link_benoit',
- 'Link (Sears)': 'link_sears',
- 'Nautical Mile' : 'nm',
- 'Nautical Mile (UK)' : 'nm_uk',
- 'US survey foot' : 'survey_ft',
- 'U.S. Foot' : 'survey_ft',
- 'Yard (Indian)' : 'indian_yd',
- 'Yard (Sears)' : 'sears_yd'
- }
- LALIAS = dict([(k.lower(), v) for k, v in ALIAS.items()])
- def __init__(self, default_unit=None, **kwargs):
- # The base unit is in meters.
- self.m, self._default_unit = self.default_units(kwargs)
- if default_unit and isinstance(default_unit, str):
- self._default_unit = default_unit
- def __getattr__(self, name):
- if name in self.UNITS:
- return self.m / self.UNITS[name]
- else:
- raise AttributeError('Unknown unit type: %s' % name)
- def __repr__(self):
- return 'Distance(%s=%s)' % (self._default_unit, getattr(self, self._default_unit))
- def __str__(self):
- return '%s %s' % (getattr(self, self._default_unit), self._default_unit)
- def __cmp__(self, other):
- if isinstance(other, Distance):
- return cmp(self.m, other.m)
- else:
- return NotImplemented
- def __add__(self, other):
- if isinstance(other, Distance):
- return Distance(default_unit=self._default_unit, m=(self.m + other.m))
- else:
- raise TypeError('Distance must be added with Distance')
- def __iadd__(self, other):
- if isinstance(other, Distance):
- self.m += other.m
- return self
- else:
- raise TypeError('Distance must be added with Distance')
- def __sub__(self, other):
- if isinstance(other, Distance):
- return Distance(default_unit=self._default_unit, m=(self.m - other.m))
- else:
- raise TypeError('Distance must be subtracted from Distance')
- def __isub__(self, other):
- if isinstance(other, Distance):
- self.m -= other.m
- return self
- else:
- raise TypeError('Distance must be subtracted from Distance')
- def __mul__(self, other):
- if isinstance(other, (int, float, long, Decimal)):
- return Distance(default_unit=self._default_unit, m=(self.m * float(other)))
- elif isinstance(other, Distance):
- return Area(default_unit='sq_' + self._default_unit, sq_m=(self.m * other.m))
- else:
- raise TypeError('Distance must be multiplied with number or Distance')
- def __imul__(self, other):
- if isinstance(other, (int, float, long, Decimal)):
- self.m *= float(other)
- return self
- else:
- raise TypeError('Distance must be multiplied with number')
- def __rmul__(self, other):
- return self * other
- def __div__(self, other):
- if isinstance(other, (int, float, long, Decimal)):
- return Distance(default_unit=self._default_unit, m=(self.m / float(other)))
- else:
- raise TypeError('Distance must be divided with number')
- def __idiv__(self, other):
- if isinstance(other, (int, float, long, Decimal)):
- self.m /= float(other)
- return self
- else:
- raise TypeError('Distance must be divided with number')
- def __nonzero__(self):
- return bool(self.m)
- class Area(MeasureBase):
- # Getting the square units values and the alias dictionary.
- UNITS = dict([('sq_%s' % k, v ** 2) for k, v in Distance.UNITS.items()])
- ALIAS = dict([(k, 'sq_%s' % v) for k, v in Distance.ALIAS.items()])
- LALIAS = dict([(k.lower(), v) for k, v in ALIAS.items()])
- def __init__(self, default_unit=None, **kwargs):
- self.sq_m, self._default_unit = self.default_units(kwargs)
- if default_unit and isinstance(default_unit, str):
- self._default_unit = default_unit
- def __getattr__(self, name):
- if name in self.UNITS:
- return self.sq_m / self.UNITS[name]
- else:
- raise AttributeError('Unknown unit type: ' + name)
- def __repr__(self):
- return 'Area(%s=%s)' % (self._default_unit, getattr(self, self._default_unit))
- def __str__(self):
- return '%s %s' % (getattr(self, self._default_unit), self._default_unit)
- def __cmp__(self, other):
- if isinstance(other, Area):
- return cmp(self.sq_m, other.sq_m)
- else:
- return NotImplemented
- def __add__(self, other):
- if isinstance(other, Area):
- return Area(default_unit=self._default_unit, sq_m=(self.sq_m + other.sq_m))
- else:
- raise TypeError('Area must be added with Area')
- def __iadd__(self, other):
- if isinstance(other, Area):
- self.sq_m += other.sq_m
- return self
- else:
- raise TypeError('Area must be added with Area')
- def __sub__(self, other):
- if isinstance(other, Area):
- return Area(default_unit=self._default_unit, sq_m=(self.sq_m - other.sq_m))
- else:
- raise TypeError('Area must be subtracted from Area')
- def __isub__(self, other):
- if isinstance(other, Area):
- self.sq_m -= other.sq_m
- return self
- else:
- raise TypeError('Area must be subtracted from Area')
- def __mul__(self, other):
- if isinstance(other, (int, float, long, Decimal)):
- return Area(default_unit=self._default_unit, sq_m=(self.sq_m * float(other)))
- else:
- raise TypeError('Area must be multiplied with number')
- def __imul__(self, other):
- if isinstance(other, (int, float, long, Decimal)):
- self.sq_m *= float(other)
- return self
- else:
- raise TypeError('Area must be multiplied with number')
- def __rmul__(self, other):
- return self * other
- def __div__(self, other):
- if isinstance(other, (int, float, long, Decimal)):
- return Area(default_unit=self._default_unit, sq_m=(self.sq_m / float(other)))
- else:
- raise TypeError('Area must be divided with number')
- def __idiv__(self, other):
- if isinstance(other, (int, float, long, Decimal)):
- self.sq_m /= float(other)
- return self
- else:
- raise TypeError('Area must be divided with number')
- def __nonzero__(self):
- return bool(self.sq_m)
- # Shortcuts
- D = Distance
- A = Area