| # 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 the default units specified |
| from the given keyword arguments dictionary. |
| """ |
| val = 0.0 |
| for unit, value in kwargs.iteritems(): |
| 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 __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 __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 |
