Coverage for pygeodesy/gars.py: 97%
144 statements
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2# -*- coding: utf-8 -*-
4u'''I{Global Area Reference System} (GARS) en-/decoding.
6Class L{Garef} and several functions to encode, decode and inspect
7GARS references.
9Transcoded from I{Charles Karney}'s C++ class U{GARS
10<https://GeographicLib.SourceForge.io/C++/doc/classGeographicLib_1_1GARS.html>}.
12@see: U{Global Area Reference System
13 <https://WikiPedia.org/wiki/Global_Area_Reference_System>} and U{NGA
14 (GARS)<https://Earth-Info.NGA.mil/GandG/coordsys/grids/gars.html>}.
15'''
17from pygeodesy.basics import isstr, _splituple, typename
18from pygeodesy.constants import _off90, _1_over, _0_5, \
19 _1_0 # PYCHOK used!
20from pygeodesy.errors import _ValueError, _xkwds, _xStrError
21# from pygeodesy.internals import typename # from .basics
22from pygeodesy.interns import NN, _0to9_, _AtoZnoIO_, _INV_
23from pygeodesy.lazily import _ALL_DOCS, _ALL_LAZY
24from pygeodesy.named import _name__, Fmt, Property_RO
25from pygeodesy.namedTuples import LatLon2Tuple, LatLonPrec3Tuple
26# from pygeodesy.props import Property_RO # from .named
27# from pygeodesy.streprs import Fmt # from .named
28from pygeodesy.units import Int_, Lat, Lon, Precision_, Scalar_, Str
30from math import floor
32__all__ = _ALL_LAZY.gars
33__version__ = '25.04.14'
35_Digits = _0to9_
36_LatLen = 2
37_LatOrig = -90
38_Letters = _AtoZnoIO_
39_LonLen = 3
40_LonOrig = -180
41_MaxPrec = 2
43_MinLen = _LonLen + _LatLen
44_MaxLen = _MinLen + _MaxPrec
46_M1 = _M2 = 2
47_M3 = 3
48_M4 = _M1 * _M2 * _M3
50_LatOrig_M4 = _LatOrig * _M4
51_LatOrig_M1 = _LatOrig * _M1
52_LonOrig_M4 = _LonOrig * _M4
53_LonOrig_M1_1 = _LonOrig * _M1 - 1
55_Resolutions = _1_over(_M1), _1_over(_M1 * _M2), _1_over(_M4)
58def _2divmod2(ll, _Orig_M4):
59 x = int(floor(ll * _M4)) - _Orig_M4
60 i = (x * _M1) // _M4
61 x -= i * _M4 // _M1
62 return i, x
65def _2fll(lat, lon, *unused):
66 '''(INTERNAL) Convert lat, lon.
67 '''
68 # lat, lon = parseDMS2(lat, lon)
69 return (Lat(lat, Error=GARSError),
70 Lon(lon, Error=GARSError))
73# def _2Garef(garef):
74# '''(INTERNAL) Check or create a L{Garef} instance.
75# '''
76# if not isinstance(garef, Garef):
77# try:
78# garef = Garef(garef)
79# except (TypeError, ValueError):
80# raise _xStrError(Garef, Str, garef=garef)
81# return garef
84def _2garstr2(garef):
85 '''(INTERNAL) Check a garef string.
86 '''
87 try:
88 n, garstr = len(garef), garef.upper()
89 if n < _MinLen or n > _MaxLen \
90 or garstr.startswith(_INV_) \
91 or not garstr.isalnum():
92 raise ValueError()
93 return garstr, _2Precision(n - _MinLen)
95 except (AttributeError, TypeError, ValueError) as x:
96 raise GARSError(typename(Garef), garef, cause=x)
99def _2Precision(precision):
100 '''(INTERNAL) Return a L{Precision_} instance.
101 '''
102 return Precision_(precision, Error=GARSError, low=0, high=_MaxPrec)
105class GARSError(_ValueError):
106 '''Global Area Reference System (GARS) encode, decode or other L{Garef} issue.
107 '''
108 pass
111class Garef(Str):
112 '''Garef class, a named C{str}.
113 '''
114 # no str.__init__ in Python 3
115 def __new__(cls, lat_gll, lon=None, precision=1, **name):
116 '''New L{Garef} from an other L{Garef} instance or garef C{str}
117 or from a lat- and longitude.
119 @arg lat_gll: Latitude (C{degrees90}), a garef (L{Garef},
120 C{str}) or a location (C{LatLon}, C{LatLon*Tuple}).
121 @kwarg lon: Logitude (C{degrees180)}, required if B{C{lat_gll}}
122 is C{degrees90}, ignored otherwise.
123 @kwarg precision: The desired garef resolution and length (C{int}
124 0..2), see L{encode<pygeodesy.gars.encode>}.
125 @kwarg name: Optional C{B{name}=NN} (C{str}).
127 @return: New L{Garef}.
129 @raise GARSError: INValid B{C{lat_gll}}.
131 @raise RangeError: Invalid B{C{lat_gll}} or B{C{lon}}.
133 @raise TypeError: Invalid B{C{lat_gll}} or B{C{lon}}.
134 '''
135 if lon is None:
136 if isinstance(lat_gll, Garef):
137 g, ll, p = str(lat_gll), lat_gll.latlon, lat_gll.precision
138 elif isstr(lat_gll):
139 ll = _splituple(lat_gll)
140 if len(ll) > 1:
141 g, ll, p = _encode3(ll[0], ll[1], precision)
142 else:
143 g, ll = lat_gll.upper(), None
144 _, p = _2garstr2(g) # validate
145 else: # assume LatLon
146 try:
147 g, ll, p = _encode3(lat_gll.lat, lat_gll.lon, precision)
148 except AttributeError:
149 raise _xStrError(Garef, gll=lat_gll, Error=GARSError)
150 else:
151 g, ll, p = _encode3(lat_gll, lon, precision)
153 self = Str.__new__(cls, g, name=_name__(name, _or_nameof=lat_gll))
154 self._latlon = ll
155 self._precision = p
156 return self
158 @Property_RO
159 def decoded3(self):
160 '''Get this garef's attributes (L{LatLonPrec3Tuple}).
161 '''
162 lat, lon = self.latlon
163 return LatLonPrec3Tuple(lat, lon, self.precision, name=self.name)
165 @Property_RO
166 def _decoded3(self):
167 '''(INTERNAL) Initial L{LatLonPrec3Tuple}.
168 '''
169 return decode3(self)
171 @Property_RO
172 def latlon(self):
173 '''Get this garef's (center) lat- and longitude (L{LatLon2Tuple}).
174 '''
175 lat, lon = self._latlon or self._decoded3[:2]
176 return LatLon2Tuple(lat, lon, name=self.name)
178 @Property_RO
179 def precision(self):
180 '''Get this garef's precision (C{int}).
181 '''
182 p = self._precision
183 return self._decoded3.precision if p is None else p
185 def toLatLon(self, LatLon=None, **LatLon_kwds):
186 '''Return (the center of) this garef cell as an instance
187 of the supplied C{LatLon} class.
189 @kwarg LatLon: Class to use (C{LatLon} or C{None}).
190 @kwarg LatLon_kwds: Optional, additional B{C{LatLon}}
191 keyword arguments.
193 @return: This garef location as B{C{LatLon}} or if
194 C{B{LatLon} is None} as L{LatLonPrec3Tuple}.
195 '''
196 return self.decoded3 if LatLon is None else LatLon(
197 *self.latlon, **_xkwds(LatLon_kwds, name=self.name))
200def decode3(garef, center=True, **name):
201 '''Decode a C{garef} to lat-, longitude and precision.
203 @arg garef: To be decoded (L{Garef} or C{str}).
204 @kwarg center: If C{True}, use the garef's center, otherwise
205 the south-west, lower-left corner (C{bool}).
207 @return: A L{LatLonPrec3Tuple}C{(lat, lon, precision)}.
209 @raise GARSError: Invalid B{C{garef}}, INValid, non-alphanumeric
210 or bad length B{C{garef}}.
211 '''
212 def _Error(i):
213 return GARSError(garef=Fmt.SQUARE(repr(garef), i))
215 def _ll(chars, g, i, j, lo, hi):
216 ll, b = 0, len(chars)
217 for i in range(i, j):
218 d = chars.find(g[i])
219 if d < 0:
220 raise _Error(i)
221 ll = ll * b + d
222 if ll < lo or ll > hi:
223 raise _Error(j)
224 return ll
226 def _ll2(lon, lat, g, i, m):
227 d = _Digits.find(g[i])
228 if d < 1 or d > m * m:
229 raise _Error(i)
230 d, r = divmod(d - 1, m)
231 lon = lon * m + r
232 lat = lat * m + (m - 1 - d)
233 return lon, lat
235 g, precision = _2garstr2(garef)
237 lon = _ll(_Digits, g, 0, _LonLen, 1, 720) + _LonOrig_M1_1
238 lat = _ll(_Letters, g, _LonLen, _MinLen, 0, 359) + _LatOrig_M1
239 if precision > 0:
240 lon, lat = _ll2(lon, lat, g, _MinLen, _M2)
241 if precision > 1:
242 lon, lat = _ll2(lon, lat, g, _MinLen + 1, _M3)
244 if center: # ll = (ll * 2 + 1) / 2
245 lon += _0_5
246 lat += _0_5
248 n = _name__(name, _or_nameof=garef)
249 r = _Resolutions[precision] # == 1.0 / unit
250 return LatLonPrec3Tuple(Lat(lat * r, Error=GARSError),
251 Lon(lon * r, Error=GARSError),
252 precision, name=n)
255def encode(lat, lon, precision=1):
256 '''Encode a lat-/longitude as a C{garef} of the given precision.
258 @arg lat: Latitude (C{degrees}).
259 @arg lon: Longitude (C{degrees}).
260 @kwarg precision: Optional, the desired C{garef} resolution
261 and length (C{int} 0..2).
263 @return: The C{garef} (C{str}).
265 @raise RangeError: Invalid B{C{lat}} or B{C{lon}}.
267 @raise GARSError: Invalid B{C{precision}}.
269 @note: The C{garef} length is M{precision + 5} and the C{garef}
270 resolution is B{30′} for B{C{precision}} 0, B{15′} for 1
271 and B{5′} for 2, respectively.
272 '''
273 g, _, _ = _encode3(lat, lon, precision)
274 return g
277def _encode3(lat, lon, precision): # MCCABE 14
278 '''Return 3-tuple C{(garef, (lat, lon), p)}.
279 '''
280 def _digit(x, y, m):
281 return _Digits[m * (m - y - 1) + x + 1],
283 def _str(chars, x, n):
284 s, b = [], len(chars)
285 for i in range(n):
286 x, i = divmod(x, b)
287 s.append(chars[i])
288 return tuple(reversed(s))
290 p = _2Precision(precision)
292 lat, lon = _2fll(lat, lon)
294 ix, x = _2divmod2( lon, _LonOrig_M4)
295 iy, y = _2divmod2(_off90(lat), _LatOrig_M4)
297 g = _str(_Digits, ix + 1, _LonLen) + \
298 _str(_Letters, iy, _LatLen)
299 if p > 0:
300 ix, x = divmod(x, _M3)
301 iy, y = divmod(y, _M3)
302 g += _digit(ix, iy, _M2)
303 if p > 1:
304 g += _digit(x, y, _M3)
306 return NN.join(g), (lat, lon), p
309def precision(res):
310 '''Determine the L{Garef} precision to meet a required (geographic)
311 resolution.
313 @arg res: The required resolution (C{degrees}).
315 @return: The L{Garef} precision (C{int} 0..2).
317 @raise ValueError: Invalid B{C{res}}.
319 @see: Function L{gars.encode} for more C{precision} details.
320 '''
321 r = Scalar_(res=res)
322 for p in range(_MaxPrec):
323 if resolution(p) <= r:
324 return p
325 return _MaxPrec
328def resolution(prec):
329 '''Determine the (geographic) resolution of a given L{Garef} precision.
331 @arg prec: The given precision (C{int}).
333 @return: The (geographic) resolution (C{degrees}).
335 @raise GARSError: Invalid B{C{prec}}.
337 @see: Function L{gars.encode} for more C{precision} details.
338 '''
339 p = Int_(prec=prec, Error=GARSError, low=-1, high=_MaxPrec + 1)
340 return _Resolutions[max(0, min(p, _MaxPrec))]
343__all__ += _ALL_DOCS(decode3, # functions
344 encode, precision, resolution)
346# **) MIT License
347#
348# Copyright (C) 2016-2025 -- mrJean1 at Gmail -- All Rights Reserved.
349#
350# Permission is hereby granted, free of charge, to any person obtaining a
351# copy of this software and associated documentation files (the "Software"),
352# to deal in the Software without restriction, including without limitation
353# the rights to use, copy, modify, merge, publish, distribute, sublicense,
354# and/or sell copies of the Software, and to permit persons to whom the
355# Software is furnished to do so, subject to the following conditions:
356#
357# The above copyright notice and this permission notice shall be included
358# in all copies or substantial portions of the Software.
359#
360# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
361# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
362# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
363# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
364# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
365# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
366# OTHER DEALINGS IN THE SOFTWARE.