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
19from pygeodesy.errors import _ValueError, _xkwds, _xStrError
20# from pygeodesy.internals import typename # from .basics
21from pygeodesy.interns import NN, _0to9_, _AtoZnoIO_, _INV_
22from pygeodesy.lazily import _ALL_DOCS, _ALL_LAZY
23from pygeodesy.named import _name__, Fmt, Property_RO
24from pygeodesy.namedTuples import LatLon2Tuple, LatLonPrec3Tuple
25# from pygeodesy.props import Property_RO # from .named
26# from pygeodesy.streprs import Fmt # from .named
27from pygeodesy.units import Int_, Lat, Lon, Precision_, Scalar_, Str
29from math import floor
31__all__ = _ALL_LAZY.gars
32__version__ = '25.05.07'
34_Digits = _0to9_
35_LatLen = 2
36_LatOrig = -90
37_Letters = _AtoZnoIO_
38_LonLen = 3
39_LonOrig = -180
40_MaxPrec = 2
42_MinLen = _LonLen + _LatLen
43_MaxLen = _MinLen + _MaxPrec
45_M1 = _M2 = 2
46_M3 = 3
47_M4 = _M1 * _M2 * _M3
49_LatOrig_M4 = _LatOrig * _M4
50_LatOrig_M1 = _LatOrig * _M1
51_LonOrig_M4 = _LonOrig * _M4
52_LonOrig_M1_1 = _LonOrig * _M1 - 1
54_Resolutions = _1_over(_M1), _1_over(_M1 * _M2), _1_over(_M4)
57def _2divmod2(ll, _Orig_M4):
58 x = int(floor(ll * _M4)) - _Orig_M4
59 i = (x * _M1) // _M4
60 x -= i * _M4 // _M1
61 return i, x
64def _2fll(lat, lon, *unused):
65 '''(INTERNAL) Convert lat, lon.
66 '''
67 # lat, lon = parseDMS2(lat, lon)
68 return (Lat(lat, Error=GARSError),
69 Lon(lon, Error=GARSError))
72# def _2Garef(garef):
73# '''(INTERNAL) Check or create a L{Garef} instance.
74# '''
75# if not isinstance(garef, Garef):
76# try:
77# garef = Garef(garef)
78# except (TypeError, ValueError):
79# raise _xStrError(Garef, Str, garef=garef)
80# return garef
83def _2garstr2(garef):
84 '''(INTERNAL) Check a garef string.
85 '''
86 try:
87 n, garstr = len(garef), garef.upper()
88 if n < _MinLen or n > _MaxLen \
89 or garstr.startswith(_INV_) \
90 or not garstr.isalnum():
91 raise ValueError()
92 return garstr, _2Precision(n - _MinLen)
94 except (AttributeError, TypeError, ValueError) as x:
95 raise GARSError(typename(Garef), garef, cause=x)
98def _2Precision(precision):
99 '''(INTERNAL) Return a L{Precision_} instance.
100 '''
101 return Precision_(precision, Error=GARSError, low=0, high=_MaxPrec)
104class GARSError(_ValueError):
105 '''Global Area Reference System (GARS) encode, decode or other L{Garef} issue.
106 '''
107 pass
110class Garef(Str):
111 '''Garef class, a named C{str}.
112 '''
113 # no str.__init__ in Python 3
114 def __new__(cls, lat_gll, lon=None, precision=1, **name):
115 '''New L{Garef} from an other L{Garef} instance or garef C{str}
116 or from a lat- and longitude.
118 @arg lat_gll: Latitude (C{degrees90}), a garef (L{Garef},
119 C{str}) or a location (C{LatLon}, C{LatLon*Tuple}).
120 @kwarg lon: Logitude (C{degrees180)}, required if B{C{lat_gll}}
121 is C{degrees90}, ignored otherwise.
122 @kwarg precision: The desired garef resolution and length (C{int}
123 0..2), see L{encode<pygeodesy.gars.encode>}.
124 @kwarg name: Optional C{B{name}=NN} (C{str}).
126 @return: New L{Garef}.
128 @raise GARSError: INValid B{C{lat_gll}}.
130 @raise RangeError: Invalid B{C{lat_gll}} or B{C{lon}}.
132 @raise TypeError: Invalid B{C{lat_gll}} or B{C{lon}}.
133 '''
134 if lon is None:
135 if isinstance(lat_gll, Garef):
136 g, ll, p = str(lat_gll), lat_gll.latlon, lat_gll.precision
137 elif isstr(lat_gll):
138 ll = _splituple(lat_gll)
139 if len(ll) > 1:
140 g, ll, p = _encode3(ll[0], ll[1], precision)
141 else:
142 g, ll = lat_gll.upper(), None
143 _, p = _2garstr2(g) # validate
144 else: # assume LatLon
145 try:
146 g, ll, p = _encode3(lat_gll.lat, lat_gll.lon, precision)
147 except AttributeError:
148 raise _xStrError(Garef, gll=lat_gll, Error=GARSError)
149 else:
150 g, ll, p = _encode3(lat_gll, lon, precision)
152 self = Str.__new__(cls, g, name=_name__(name, _or_nameof=lat_gll))
153 self._latlon = ll
154 self._precision = p
155 return self
157 @Property_RO
158 def decoded3(self):
159 '''Get this garef's attributes (L{LatLonPrec3Tuple}).
160 '''
161 lat, lon = self.latlon
162 return LatLonPrec3Tuple(lat, lon, self.precision, name=self.name)
164 @Property_RO
165 def _decoded3(self):
166 '''(INTERNAL) Initial L{LatLonPrec3Tuple}.
167 '''
168 return decode3(self)
170 @Property_RO
171 def latlon(self):
172 '''Get this garef's (center) lat- and longitude (L{LatLon2Tuple}).
173 '''
174 lat, lon = self._latlon or self._decoded3[:2]
175 return LatLon2Tuple(lat, lon, name=self.name)
177 @Property_RO
178 def precision(self):
179 '''Get this garef's precision (C{int}).
180 '''
181 p = self._precision
182 return self._decoded3.precision if p is None else p
184 def toLatLon(self, LatLon=None, **LatLon_kwds):
185 '''Return (the center of) this garef cell as an instance
186 of the supplied C{LatLon} class.
188 @kwarg LatLon: Class to use (C{LatLon} or C{None}).
189 @kwarg LatLon_kwds: Optional, additional B{C{LatLon}}
190 keyword arguments.
192 @return: This garef location as B{C{LatLon}} or if
193 C{B{LatLon} is None} as L{LatLonPrec3Tuple}.
194 '''
195 return self.decoded3 if LatLon is None else LatLon(
196 *self.latlon, **_xkwds(LatLon_kwds, name=self.name))
199def decode3(garef, center=True, **name):
200 '''Decode a C{garef} to lat-, longitude and precision.
202 @arg garef: To be decoded (L{Garef} or C{str}).
203 @kwarg center: If C{True}, use the garef's center, otherwise
204 the south-west, lower-left corner (C{bool}).
206 @return: A L{LatLonPrec3Tuple}C{(lat, lon, precision)}.
208 @raise GARSError: Invalid B{C{garef}}, INValid, non-alphanumeric
209 or bad length B{C{garef}}.
210 '''
211 def _Error(i):
212 return GARSError(garef=Fmt.SQUARE(repr(garef), i))
214 def _ll(chars, g, i, j, lo, hi):
215 ll, b = 0, len(chars)
216 for i in range(i, j):
217 d = chars.find(g[i])
218 if d < 0:
219 raise _Error(i)
220 ll = ll * b + d
221 if ll < lo or ll > hi:
222 raise _Error(j)
223 return ll
225 def _ll2(lon, lat, g, i, m):
226 d = _Digits.find(g[i])
227 if d < 1 or d > m * m:
228 raise _Error(i)
229 d, r = divmod(d - 1, m)
230 lon = lon * m + r
231 lat = lat * m + (m - 1 - d)
232 return lon, lat
234 g, precision = _2garstr2(garef)
236 lon = _ll(_Digits, g, 0, _LonLen, 1, 720) + _LonOrig_M1_1
237 lat = _ll(_Letters, g, _LonLen, _MinLen, 0, 359) + _LatOrig_M1
238 if precision > 0:
239 lon, lat = _ll2(lon, lat, g, _MinLen, _M2)
240 if precision > 1:
241 lon, lat = _ll2(lon, lat, g, _MinLen + 1, _M3)
243 if center: # ll = (ll * 2 + 1) / 2
244 lon += _0_5
245 lat += _0_5
247 n = _name__(name, _or_nameof=garef)
248 r = _Resolutions[precision] # == 1.0 / unit
249 return LatLonPrec3Tuple(Lat(lat * r, Error=GARSError),
250 Lon(lon * r, Error=GARSError),
251 precision, name=n)
254def encode(lat, lon, precision=1):
255 '''Encode a lat-/longitude as a C{garef} of the given precision.
257 @arg lat: Latitude (C{degrees}).
258 @arg lon: Longitude (C{degrees}).
259 @kwarg precision: Optional, the desired C{garef} resolution
260 and length (C{int} 0..2).
262 @return: The C{garef} (C{str}).
264 @raise RangeError: Invalid B{C{lat}} or B{C{lon}}.
266 @raise GARSError: Invalid B{C{precision}}.
268 @note: The C{garef} length is M{precision + 5} and the C{garef}
269 resolution is B{30′} for B{C{precision}} 0, B{15′} for 1
270 and B{5′} for 2, respectively.
271 '''
272 g, _, _ = _encode3(lat, lon, precision)
273 return g
276def _encode3(lat, lon, precision): # MCCABE 14
277 '''Return 3-tuple C{(garef, (lat, lon), p)}.
278 '''
279 def _digit(x, y, m):
280 return _Digits[m * (m - y - 1) + x + 1],
282 def _str(chars, x, n):
283 s, b = [], len(chars)
284 for i in range(n):
285 x, i = divmod(x, b)
286 s.append(chars[i])
287 return tuple(reversed(s))
289 p = _2Precision(precision)
291 lat, lon = _2fll(lat, lon)
293 ix, x = _2divmod2( lon, _LonOrig_M4)
294 iy, y = _2divmod2(_off90(lat), _LatOrig_M4)
296 g = _str(_Digits, ix + 1, _LonLen) + \
297 _str(_Letters, iy, _LatLen)
298 if p > 0:
299 ix, x = divmod(x, _M3)
300 iy, y = divmod(y, _M3)
301 g += _digit(ix, iy, _M2)
302 if p > 1:
303 g += _digit(x, y, _M3)
305 return NN.join(g), (lat, lon), p
308def precision(res):
309 '''Determine the L{Garef} precision to meet a required (geographic)
310 resolution.
312 @arg res: The required resolution (C{degrees}).
314 @return: The L{Garef} precision (C{int} 0..2).
316 @raise ValueError: Invalid B{C{res}}.
318 @see: Function L{gars.encode} for more C{precision} details.
319 '''
320 r = Scalar_(res=res)
321 for p in range(_MaxPrec):
322 if resolution(p) <= r:
323 return p
324 return _MaxPrec
327def resolution(prec):
328 '''Determine the (geographic) resolution of a given L{Garef} precision.
330 @arg prec: The given precision (C{int}).
332 @return: The (geographic) resolution (C{degrees}).
334 @raise GARSError: Invalid B{C{prec}}.
336 @see: Function L{gars.encode} for more C{precision} details.
337 '''
338 p = Int_(prec=prec, Error=GARSError, low=-1, high=_MaxPrec + 1)
339 return _Resolutions[max(0, min(p, _MaxPrec))]
342__all__ += _ALL_DOCS(decode3, # functions
343 encode, precision, resolution)
345# **) MIT License
346#
347# Copyright (C) 2016-2025 -- mrJean1 at Gmail -- All Rights Reserved.
348#
349# Permission is hereby granted, free of charge, to any person obtaining a
350# copy of this software and associated documentation files (the "Software"),
351# to deal in the Software without restriction, including without limitation
352# the rights to use, copy, modify, merge, publish, distribute, sublicense,
353# and/or sell copies of the Software, and to permit persons to whom the
354# Software is furnished to do so, subject to the following conditions:
355#
356# The above copyright notice and this permission notice shall be included
357# in all copies or substantial portions of the Software.
358#
359# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
360# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
361# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
362# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
363# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
364# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
365# OTHER DEALINGS IN THE SOFTWARE.