1

2# -*- coding: utf-8 -*-

3

4 u'''Albers Equal-Area projections.

5

6 Classes L{AlbersEqualArea}, L{AlbersEqualArea2}, L{AlbersEqualArea4},

7 L{AlbersEqualAreaCylindrical}, L{AlbersEqualAreaNorth}, L{AlbersEqualAreaSouth}

8 and L{AlbersError}, transcoded from I{Charles Karney}'s C++ class U{AlbersEqualArea

9<https://GeographicLib.SourceForge.io/C++/doc/classGeographicLib_1_1AlbersEqualArea.html>}.

10

11 See also I{Albers Equal-Area Conic Projection} in U{John P. Snyder, "Map Projections

12-- A Working Manual", 1987<https://Pubs.USGS.gov/pp/1395/report.pdf>}, pp 98-106

13 and the Albers Conical Equal-Area examples on pp 291-294.

14'''

15# make sure int/int division yields float quotient, see .basics

16 from __future__ import division as _; del _ # PYCHOK semicolon

17

18 from pygeodesy.basics import _isin, neg, neg_

19 from pygeodesy.constants import EPS0, EPS02, _EPSqrt as _TOL, \

20 _0_0, _0_5, _1_0, _N_1_0, _2_0, \

21 _N_2_0, _4_0, _6_0, _90_0, _N_90_0

22 from pygeodesy.datums import _ellipsoidal_datum, _WGS84

23 from pygeodesy.errors import _ValueError, _xkwds

24 from pygeodesy.fmath import hypot, hypot1, sqrt3

25 from pygeodesy.fsums import Fsum, _Fsum1f_, fsum1f_

26 from pygeodesy.interns import NN, _COMMASPACE_, _datum_, _gamma_, _k0_, \

27 _lat_, _lat1_, _lat2_, _lon_, _negative_, \

28 _scale_, _SPACE_, _x_, _y_

29 from pygeodesy.karney import _diff182, _norm180, _signBit

30 from pygeodesy.lazily import _ALL_DOCS, _ALL_LAZY

31 from pygeodesy.named import _name2__, _NamedBase, _NamedTuple, _Pass

32 from pygeodesy.props import deprecated_Property_RO, Property_RO, _update_all

33 from pygeodesy.streprs import Fmt, strs, unstr

34 from pygeodesy.units import Bearing, Float_, Lat, Lat_, Lon, Meter, Scalar_

35 from pygeodesy.utily import atan1, atan1d, atan2, degrees360, sincos2, \

36 sincos2d, sincos2d_

37

38 from math import atanh, degrees, fabs, radians, sqrt

39

40__all__ = _ALL_LAZY.albers

41__version__ = '25.04.14'

42

43_k1_ = 'k1'

44_NUMIT = 9 # XXX 4?

45_NUMIT0 = 41 # XXX 21?

46_TERMS = 31 # XXX 16?

47_TOL0 = sqrt3(_TOL)

48

49

50 def _ct2(s, c):

51 '''(INTERNAL) Avoid singularities at poles.

52 '''

53 c = max(EPS0, c)

54 return c, (s / c)

55

56

57 def _Ks(**name_k):

58 '''(INTERNAL) Scale C{B{k} >= EPS0}.

59 '''

60 return Scalar_(Error=AlbersError, low=EPS0, **name_k) # > 0

61

62

63 def _Lat(*lat, **Error_name_lat):

64 '''(INTERNAL) Latitude C{-90 <= B{lat} <= 90}.

65 '''

66 kwds = _xkwds(Error_name_lat, Error=AlbersError)

67 return Lat_(*lat, **kwds)

68

69

70 def _qZx(albs):

71 '''(INTERNAL) Set C{albs._qZ} and C{albs._qx}.

72 '''

73 E = albs._datum.ellipsoid # _AlbersBase

74 albs._qZ = qZ = _1_0 + E.e21 * _atanheE(_1_0, E)

75 albs._qx = qZ / (_2_0 * E.e21)

76 return qZ

77

78

79 class AlbersError(_ValueError):

80 '''An L{AlbersEqualArea}, L{AlbersEqualArea2}, L{AlbersEqualArea4},

81 L{AlbersEqualAreaCylindrical}, L{AlbersEqualAreaNorth},

82 L{AlbersEqualAreaSouth} or L{Albers7Tuple} issue.

83 '''

84 pass

85

86

87 class _AlbersBase(_NamedBase):

88 '''(INTERNAL) Base class for C{AlbersEqualArea...} projections.

89

90 @see: I{Karney}'s C++ class U{AlbersEqualArea<https://GeographicLib.SourceForge.io/

91 C++/doc/classGeographicLib_1_1AlbersEqualArea.html>}, method C{Init}.

92 '''

93 _datum = _WGS84

94 _k = NN # or _k0_ or _k1_

95 _k0 = _Ks(k0=_1_0)

96# _k0n0 = None # (INTERNAL) k0 * no

97 _k02 = _1_0 # (INTERNAL) k0**2

98# _k02n0 = None # (INTERNAL) k02 * n0

99# _lat0 = None # lat origin

100 _lat1 = None # let 1st parallel

101 _lat2 = None # lat 2nd parallel

102 _m0 = _0_0 # if polar else sqrt(m02)

103# _m02 = None # (INTERNAL) cached

104# _n0 = None # (INTERNAL) cached

105 _nrho0 = _0_0 # if polar else m0 * E.a

106 _polar = False

107 _qx = None # (INTERNAL) see _qZx

108 _qZ = None # (INTERNAL) see _qZx

109# _scxi0_ = None # (INTERNAL) sec(xi) / (qZ * E.a2)

110 _sign = +1

111# _sxi0 = None # (INTERNAL) sin(xi)

112# _txi0 = None # (INTERNAL) tan(xi)

113

114 def __init__(self, sa1, ca1, sa2, ca2, k, datum, **name):

115 '''(INTERNAL) New C{AlbersEqualArea...} instance.

116 '''

117 qZ = self._qZ

118 if not _isin(datum, None, self._datum):

119 self._datum = _ellipsoidal_datum(datum, **name)

120 qZ = _qZx(self)

121 elif qZ is None:

122 qZ = _qZx(_AlbersBase)

123 if name:

124 self.name = name

125

126 E = self.ellipsoid

127 c = min(ca1, ca2)

128 if _signBit(c):

129 raise AlbersError(clat1=ca1, clat2=ca2, txt=_negative_)

130 polar = c < EPS0 # == 0

131

132 # determine hemisphere of tangent latitude

133 if sa1 < 0: # and sa2 < 0:

134 self._sign = -1

135 # internally, tangent latitude positive

136 sa1, sa2 = neg_(sa1, sa2)

137 if sa1 > sa2: # make phi1 < phi2

138 sa1, sa2 = sa2, sa1

139 ca1, ca2 = ca2, ca1

140 if sa1 < 0: # or sa2 < 0:

141 raise AlbersError(slat1=sa1, slat2=sa2, txt=_negative_)

142 ca1, ta1 = _ct2(sa1, ca1)

143 ca2, ta2 = _ct2(sa2, ca2)

144

145 par1 = fabs(ta1 - ta2) < EPS02 # ta1 == ta2

146 ta0, C = (ta2, _1_0) if par1 or polar else \

147 self._ta0C2(ca1, sa1, ta1, ca2, sa2, ta2)

148

149 self._lat0 = _Lat(lat0=self._sign * atan1d(ta0))

150 self._m02 = m02 = _1_x21(E.f1 * ta0)

151 self._n0 = n0 = ta0 / hypot1(ta0)

152 if polar:

153 self._polar = True

154# self._nrho0 = self._m0 = _0_0

155 else: # m0 = nrho0 / E.a

156 self._m0 = t = sqrt(m02)

157 self._nrho0 = t * E.a

158 t = self._txi0 = self._txif(ta0)

159 h = hypot1(t)

160 s = self._sxi0 = t / h

161 if par1:

162 self._k0n0 = self._k02n0 = n0

163 else:

164 self._k0s(k * sqrt(C / (m02 + n0 * qZ * s)))

165 self._scxi0_ = h / (qZ * E.a2)

166

167 def _a_b_sxi3(self, *ca_sa_ta_scb_4s):

168 '''(INTERNAL) Sum of C{sm1} terms and C{sin(xi)}s for ._ta0C2.

169 '''

170 _1 = _1_0

171 a = b = s = _0_0

172 for ca, sa, ta, scb in ca_sa_ta_scb_4s:

173 cxi, sxi, _ = self._cstxif3(ta)

174 if sa > 0:

175 sa += _1

176 a += (cxi / ca)**2 * sa / (sxi + _1)

177 b += scb * ca**2 / sa

178 else:

179 sa = _1 - sa

180 a += (_1 - sxi) / sa

181 b += scb * sa

182 s += sxi

183 return a, b, s

184

185 def _azik(self, t, ta):

186 '''(INTERNAL) Compute the azimuthal scale C{_Ks(k=k)}.

187 '''

188 E = self.ellipsoid

189 return _Ks(k=hypot1(E.b_a * ta) * self._k0 * t / E.a)

190

191 def _cstxif3(self, ta):

192 '''(INTERNAL) Get 3-tuple C{(cos, sin, tan)} of M{xi(ta)}.

193 '''

194 t = self._txif(ta)

195 c = _1_0 / hypot1(t)

196 s = c * t

197 return c, s, t

198

199 @Property_RO

200 def datum(self):

201 '''Get the datum (L{Datum}).

202 '''

203 return self._datum

204

205 @Property_RO

206 def ellipsoid(self):

207 '''Get the datum's ellipsoid (L{Ellipsoid}).

208 '''

209 return self.datum.ellipsoid

210

211 @Property_RO

212 def equatoradius(self):

213 '''Get the C{ellipsoid}'s equatorial radius, semi-axis (C{meter}).

214 '''

215 return self.ellipsoid.a

216

217 a = equatoradius

218

219 @Property_RO

220 def flattening(self):

221 '''Get the C{ellipsoid}'s flattening (C{scalar}).

222 '''

223 return self.ellipsoid.f

224

225 f = flattening

226

227 def forward(self, lat, lon, lon0=0, **name):

228 '''Convert a geodetic location to east- and northing.

229

230 @arg lat: Latitude of the location (C{degrees}).

231 @arg lon: Longitude of the location (C{degrees}).

232 @kwarg lon0: Optional central meridian longitude (C{degrees}).

233 @kwarg name: Optional C{B{name}=NN} for the location (C{str}).

234

235 @return: An L{Albers7Tuple}C{(x, y, lat, lon, gamma, scale, datum)},

236 with C{lon} offset by B{C{lon0}} and reduced C{[-180,180]}.

237

238 @note: The origin latitude is returned by C{property lat0}. No

239 false easting or northing is added. The value of B{C{lat}}

240 should be in the range C{[-90..90] degrees}. The returned

241 values C{x} and C{y} will be large but finite for points

242 projecting to infinity, i.e. one or both of the poles.

243 '''

244 a = self.ellipsoid.a

245 s = self._sign

246

247 k0 = self._k0

248 n0 = self._n0

249 nrho0 = self._nrho0

250 txi0 = self._txi0

251

252 _, ta = _ct2(*sincos2d(s * _Lat(lat=lat)))

253

254 _, sxi, txi = self._cstxif3(ta)

255 dq = _Dsn(txi, txi0, sxi, self._sxi0) * \

256 (txi - txi0) * self._qZ

257 drho = a * dq / (sqrt(self._m02 - n0 * dq) + self._m0)

258

259 lon, _ = _diff182(lon0, lon)

260 x = radians(lon)

261 th = self._k02n0 * x

262 sth, cth = sincos2(th) # XXX sin, cos

263 if n0:

264 x = sth / n0

265 y = (_1_0 - cth) if cth < 0 else (sth**2 / (cth + _1_0))

266 y *= nrho0 / n0

267 else:

268 x *= self._k02

269 y = _0_0

270 t = nrho0 - n0 * drho

271 x = t * x / k0

272 y = s * (y + drho * cth) / k0

273

274 g = degrees360(s * th)

275 if t:

276 k0 = self._azik(t, ta)

277 return Albers7Tuple(x, y, lat, lon, g, k0, self.datum,

278 name=self._name__(name))

279

280 @Property_RO

281 def ispolar(self):

282 '''Is this projection polar (C{bool})?

283 '''

284 return self._polar

285

286 isPolar = ispolar # synonym

287

288 def _k0s(self, k0):

289 '''(INTERNAL) Set C{._k0}, C{._k02}, etc.

290 '''

291 self._k0 = k0 = _Ks(k0=k0)

292 self._k02 = k02 = k0**2

293 self._k0n0 = k0 * self._n0

294 self._k02n0 = k02 * self._n0

295

296 @Property_RO

297 def lat0(self):

298 '''Get the latitude of the projection origin (C{degrees}).

299

300 This is the latitude of minimum azimuthal scale and

301 equals the B{C{lat}} in the 1-parallel L{AlbersEqualArea}

302 and lies between B{C{lat1}} and B{C{lat2}} for the

303 2-parallel L{AlbersEqualArea2} and L{AlbersEqualArea4}

304 projections.

305 '''

306 return self._lat0

307

308 @Property_RO

309 def lat1(self):

310 '''Get the latitude of the first parallel (C{degrees}).

311 '''

312 return self._lat1

313

314 @Property_RO

315 def lat2(self):

316 '''Get the latitude of the second parallel (C{degrees}).

317

318 @note: The second and first parallel latitudes are the

319 same instance for 1-parallel C{AlbersEqualArea*}

320 projections.

321 '''

322 return self._lat2

323

324 @deprecated_Property_RO

325 def majoradius(self): # PYCHOK no cover

326 '''DEPRECATED, use property C{equatoradius}.'''

327 return self.equatoradius

328

329 def rescale0(self, lat, k=1): # PYCHOK no cover

330 '''Set the azimuthal scale for this projection.

331

332 @arg lat: Northern latitude (C{degrees}).

333 @arg k: Azimuthal scale at latitude B{C{lat}} (C{scalar}).

334

335 @raise AlbersError: Invalid B{C{lat}} or B{C{k}}.

336

337 @note: This allows a I{latitude of conformality} to be specified.

338 '''

339 k0 = _Ks(k=k) / self.forward(lat, _0_0).scale

340 if self._k0 != k0:

341 _update_all(self)

342 self._k0s(k0)

343

344 def reverse(self, x, y, lon0=0, LatLon=None, **name_LatLon_kwds):

345 '''Convert an east- and northing location to geodetic lat- and longitude.

346

347 @arg x: Easting of the location (C{meter}).

348 @arg y: Northing of the location (C{meter}).

349 @kwarg lon0: Optional central meridian longitude (C{degrees}).

350 @kwarg LatLon: Class to use (C{LatLon}) or C{None}.

351 @kwarg name_LatLon_kwds: Optional C{B{name}=NN} for the location

352 and optional, additional B{C{LatLon}} keyword

353 arguments, ignored if C{B{LatLon} is None}.

354

355 @return: The geodetic (C{LatLon}) or if C{B{LatLon} is None} an

356 L{Albers7Tuple}C{(x, y, lat, lon, gamma, scale, datum)}.

357

358 @note: The origin latitude is returned by C{property lat0}. No

359 false easting or northing is added. The returned value of

360 C{lon} is in the range C{[-180..180] degrees} and C{lat}

361 is in the range C{[-90..90] degrees}. If the given

362 B{C{x}} or B{C{y}} point is outside the valid projected

363 space the nearest pole is returned.

364 '''

365 k0 = self._k0

366 n0 = self._n0

367 k0n0 = self._k0n0

368 s = self._sign

369 txi = self._txi0

370

371 x = Meter(x=x)

372 nx = k0n0 * x

373 y = Meter(y=y)

374 y_ = s * y

375 ny = k0n0 * y_

376 t = nrho0 = self._nrho0

377 y1 = nrho0 - ny

378

379 den = hypot(nx, y1) + nrho0 # 0 implies origin with polar aspect

380 if den:

381 drho = _Fsum1f_(x * nx, y_ * nrho0 * _N_2_0, y_ * ny).fover(den / k0)

382 # dsxia = scxi0 * dsxi

383 t += drho * n0 # k0 below

384 d_ = (nrho0 + t) * drho * self._scxi0_ # / (qZ * E.a2)

385 t_ = txi - d_

386 d_ = (txi + t_) * d_ + _1_0

387 txi = t_ / (sqrt(d_) if d_ > EPS02 else EPS0)

388

389 ta = self._tanf(txi)

390 lat = atan1d(s * ta)

391

392 th = atan2(nx, y1)

393 lon = degrees((th / self._k02n0) if n0 else (x / (y1 * k0)))

394 if lon0:

395 lon += _norm180(lon0)

396 lon = _norm180(lon)

397

398 n, LatLon_kwds = _name2__(name_LatLon_kwds, _or_nameof=self)

399 if LatLon is None:

400 g = degrees360(s * th)

401 if den:

402 k0 = self._azik(t, ta)

403 r = Albers7Tuple(x, y, lat, lon, g, k0, self.datum, name=n)

404 else: # PYCHOK no cover

405 kwds = _xkwds(LatLon_kwds, datum=self.datum, name=n)

406 r = LatLon(lat, lon, **kwds)

407 return r

408

409 @Property_RO

410 def scale0(self):

411 '''Get the central scale for the projection (C{float}).

412

413 This is the azimuthal scale on the latitude of origin

414 of the projection, see C{property lat0}.

415 '''

416 return self._k0

417

418 def _ta0(self, s1_qZ, ta0, E):

419 '''(INTERNAL) Refine C{ta0} for C{._ta0C2}.

420 '''

421 e2 = E.e2

422 e21 = E.e21

423 e22 = E.e22 # == e2 / e21

424 tol = _tol(_TOL0, ta0)

425 _Ta02 = Fsum(ta0).fsum2f_

426 _1, _2 = _1_0, _2_0

427 _4, _6 = _4_0, _6_0

428 for self._iteration in range(1, _NUMIT0): # 4 trips

429 ta02 = ta0**2

430 sca02 = ta02 + _1

431 sca0 = sqrt(sca02)

432 sa0 = ta0 / sca0

433 sa01 = sa0 + _1

434 sa02 = sa0**2

435 # sa0m = 1 - sa0 = 1 / (sec(a0) * (tan(a0) + sec(a0)))

436 sa0m = _1 / (sca0 * (ta0 + sca0)) # scb0^2 * sa0

437 sa0m1 = sa0m / (_1 - e2 * sa0)

438 sa021 = _1 - e2 * sa02

439

440 g = (_1 + ta02 * e21) * sa0

441 dg = (_1 + ta02 * _2) * sca02 * e21 + e2

442 D = (_1 - (_1 + sa0 * _2 * sa01) * e2) * sa0m / (e21 * sa01) # dD/dsa0

443 dD = (_2 - (_6 + sa0 * _4) * sa02 * e2) / (e21 * sa01**2)

444 BA = (_atanh1(e2 * sa0m1**2) * e21 - e2 * sa0m) * sa0m1 \

445 - (_2 + (_1 + e2) * sa0) * sa0m**2 * e22 / sa021 # B + A

446 d = (_4 - (_1 + sa02) * e2 * _2) * e22 / (sa021**2 * sca02) # dAB

447 u = fsum1f_(s1_qZ * g, -D, g * BA)

448 du = fsum1f_(s1_qZ * dg, dD, dg * BA, g * d)

449 ta0, d = _Ta02(-u / du * (sca0 * sca02))

450 if fabs(d) < tol:

451 return ta0

452 raise AlbersError(Fmt.no_convergence(d, tol), txt=repr(self))

453

454 def _ta0C2(self, ca1, sa1, ta1, ca2, sa2, ta2):

455 '''(INTERNAL) Compute C{ta0} and C{C} for C{.__init__}.

456 '''

457 E = self.ellipsoid

458 f1, e2 = E.f1, E.e2

459 _1 = _1_0

460

461 tb1 = f1 * ta1

462 tb2 = f1 * ta2

463 dtb12 = f1 * (tb1 + tb2)

464 scb12 = _1 + tb1**2

465 scb22 = _1 + tb2**2

466

467 dsn_2 = _Dsn(ta2, ta1, sa2, sa1) * _0_5

468 sa12 = sa1 * sa2

469

470 esa1_2 = (_1 - e2 * sa1**2) \

471 * (_1 - e2 * sa2**2)

472 esa12 = _1 + e2 * sa12

473

474 axi, bxi, sxi = self._a_b_sxi3((ca1, sa1, ta1, scb12),

475 (ca2, sa2, ta2, scb22))

476

477 dsxi = ((esa12 / esa1_2) + _DatanheE(sa2, sa1, E)) * dsn_2 / self._qx

478 C = _Fsum1f_(sxi * dtb12 / dsxi, scb22, scb12).fover(scb22 * scb12 * _2_0)

479

480 S = _Fsum1f_(sa1, sa2, sa12)

481 axi *= (S * e2 + _1).fover(S + _1, raiser=False)

482 bxi *= _Fsum1f_( sa1, sa2, esa12).fover(esa1_2) * e2 + \

483 _D2atanheE(sa1, sa2, E) * E.e21

484 s1_qZ = (axi * self._qZ - bxi) * dsn_2 / dtb12

485 ta0 = self._ta0(s1_qZ, (ta1 + ta2) * _0_5, E)

486 return ta0, C

487

488 def _tanf(self, txi): # in .Ellipsoid.auxAuthalic

489 '''(INTERNAL) Function M{tan-phi from tan-xi}.

490 '''

491 e2 = self.ellipsoid.e2

492 ta = txi

493 tol = _tol(_TOL, ta)

494 _Ta2 = Fsum(ta).fsum2f_

495 for self._iteration in range(1, _NUMIT): # max 2, mean 1.99

496 # dtxi / dta = (scxi / sca)^3 * 2 * (1 - e^2)

497 # / (qZ * (1 - e^2 * sa^2)^2)

498 ta2 = ta**2

499 sca2 = _1_0 + ta2

500 txia = self._txif(ta)

501 s3 = sqrt3(sca2 / (txia**2 + _1_0)) # * _1_x21(txia)

502 s3 *= (e2 * ta2 / sca2 - _1_0)**2 * self._qx

503 ta, d = _Ta2((txi - txia) * s3)

504 if fabs(d) < tol:

505 return ta

506 raise AlbersError(Fmt.no_convergence(d, tol), txt=repr(self))

507

508 def toRepr(self, prec=6, **unused): # PYCHOK expected

509 '''Return a string representation of this projection.

510

511 @kwarg prec: Number of (decimal) digits, unstripped (C{int}).

512

513 @return: This projection as C{"<classname>(lat1, lat2, ...)"}

514 (C{str}).

515 '''

516 t = self.toStr(prec=prec, sep=_COMMASPACE_)

517 return Fmt.PAREN(self.classname, t)

518

519 def toStr(self, prec=6, sep=_SPACE_, **unused): # PYCHOK expected

520 '''Return a string representation of this projection.

521

522 @kwarg prec: Number of (decimal) digits, unstripped (C{int}).

523 @kwarg sep: Separator to join (C{str}).

524

525 @return: This projection as C{"lat1 lat2"} (C{str}).

526 '''

527 k = self._k

528 t = (self.lat1, self.lat2, self._k0) if k is _k1_ else (

529 (self.lat1, self._k0) if k is _k0_ else

530 (self.lat1,))

531 t = strs(t, prec=prec)

532 if k:

533 t = t[:-1] + (Fmt.EQUAL(k, t[-1]),)

534 if self.datum != _WGS84:

535 t += Fmt.EQUAL(datum=self.datum),

536 if self.name:

537 t += Fmt.EQUAL(name=repr(self.name)),

538 return t if sep is None else sep.join(t)

539

540 def _txif(self, ta): # in .Ellipsoid.auxAuthalic

541 '''(INTERNAL) Function M{tan-xi from tan-phi}.

542 '''

543 E = self.ellipsoid

544 ca2 = _1_x21(ta)

545 sa = sqrt(ca2) * fabs(ta) # enforce odd parity

546 sa1 = _1_0 + sa

547

548 es1 = sa * E.e2

549 es1m1 = sa1 * (_1_0 - es1)

550 es1p1 = sa1 / (_1_0 + es1)

551 es2m1 = _1_0 - sa * es1

552 es2m1a = es2m1 * E.e21 # e2m

553 s = ca2 / (es1p1 * es2m1a) + _atanheE(ca2 / es1m1, E)

554 s *= es1m1 / es2m1a + _atanheE( es1p1, E)

555 t = _Fsum1f_( sa / es2m1, _atanheE( sa, E)).fover(sqrt(s))

556 return neg(t) if ta < 0 else t

557

558

559 class AlbersEqualArea(_AlbersBase):

560 '''An Albers equal-area (authalic) projection with a single standard parallel.

561

562 @see: L{AlbersEqualArea2} and L{AlbersEqualArea4}.

563 '''

564 _k = _k0_

565

566 def __init__(self, lat, k0=1, datum=_WGS84, **name):

567 '''New L{AlbersEqualArea} projection.

568

569 @arg lat: Standard parallel (C{degrees}).

570 @kwarg k0: Azimuthal scale on the standard parallel (C{scalar}).

571 @kwarg datum: Optional datum or ellipsoid (L{Datum}, L{Ellipsoid},

572 L{Ellipsoid2} or L{a_f2Tuple}).

573 @kwarg name: Optional C{B{name}=NN} for the projection (C{str}).

574

575 @raise AlbersError: Invalid B{C{lat}}, B{C{k0}} or no convergence.

576 '''

577 self._lat1 = self._lat2 = lat = _Lat(lat1=lat)

578 args = tuple(sincos2d(lat)) * 2 + (_Ks(k0=k0), datum)

579 _AlbersBase.__init__(self, *args, **name)

580

581

582 class AlbersEqualArea2(_AlbersBase):

583 '''An Albers equal-area (authalic) projection with two standard parallels.

584

585 @see: L{AlbersEqualArea} and L{AlbersEqualArea4}.

586 '''

587 _k = _k1_

588

589 def __init__(self, lat1, lat2, k1=1, datum=_WGS84, **name):

590 '''New L{AlbersEqualArea2} projection.

591

592 @arg lat1: First standard parallel (C{degrees}).

593 @arg lat2: Second standard parallel (C{degrees}).

594 @kwarg k1: Azimuthal scale on the standard parallels (C{scalar}).

595 @kwarg datum: Optional datum or ellipsoid (L{Datum}, L{Ellipsoid},

596 L{Ellipsoid2} or L{a_f2Tuple}).

597 @kwarg name: Optional C{B{name}=NN} for the projection (C{str}).

598

599 @raise AlbersError: Invalid B{C{lat1}}m B{C{lat2}}, B{C{k1}}

600 or no convergence.

601 '''

602 self._lat1, self._lat2 = lats = _Lat(lat1=lat1), _Lat(lat2=lat2)

603 args = tuple(sincos2d_(*lats)) + (_Ks(k1=k1), datum)

604 _AlbersBase.__init__(self, *args, **name)

605

606

607 class AlbersEqualArea4(_AlbersBase):

608 '''An Albers equal-area (authalic) projection specified by the C{sin}

609 and C{cos} of both standard parallels.

610

611 @see: L{AlbersEqualArea} and L{AlbersEqualArea2}.

612 '''

613 _k = _k1_

614

615 def __init__(self, slat1, clat1, slat2, clat2, k1=1, datum=_WGS84, **name):

616 '''New L{AlbersEqualArea4} projection.

617

618 @arg slat1: Sine of first standard parallel (C{scalar}).

619 @arg clat1: Cosine of first standard parallel (non-negative C{scalar}).

620 @arg slat2: Sine of second standard parallel (C{scalar}).

621 @arg clat2: Cosine of second standard parallel (non-negative C{scalar}).

622 @kwarg k1: Azimuthal scale on the standard parallels (C{scalar}).

623 @kwarg datum: Optional datum or ellipsoid (L{Datum}, L{Ellipsoid},

624 L{Ellipsoid2} or L{a_f2Tuple}).

625 @kwarg name: Optional C{B{name}=NN} for the projection (C{str}).

626

627 @raise AlbersError: Negative B{C{clat1}} or B{C{clat2}}, B{C{slat1}}

628 and B{C{slat2}} have opposite signs (hemispheres),

629 invalid B{C{k1}} or no convergence.

630 '''

631 def _Lat_s_c3(n, s, c):

632 r = Float_(hypot(s, c), name=n, Error=AlbersError)

633 L = _Lat( atan1d(s, c), name=n)

634 return L, (s / r), (c / r)

635

636 self._lat1, sa1, ca1 = _Lat_s_c3(_lat1_, slat1, clat1)

637 self._lat2, sa2, ca2 = _Lat_s_c3(_lat2_, slat2, clat2)

638 _AlbersBase.__init__(self, sa1, ca1, sa2, ca2, _Ks(k1=k1), datum, **name)

639

640

641 class AlbersEqualAreaCylindrical(_AlbersBase):

642 '''An L{AlbersEqualArea} projection at C{lat=0} and C{k0=1} degenerating

643 to the cylindrical-equal-area projection.

644 '''

645 _lat1 = _lat2 = _Lat(lat1=_0_0)

646

647 def __init__(self, lat=_0_0, datum=_WGS84, **name):

648 '''New L{AlbersEqualAreaCylindrical} projection.

649

650 @kwarg lat: Standard parallel (C{0 degrees} I{fixed}).

651 @kwarg datum: Optional datum or ellipsoid (L{Datum}, L{Ellipsoid},

652 L{Ellipsoid2} or L{a_f2Tuple}).

653 @kwarg name: Optional C{B{name}=NN} for the projection (C{str}).

654 '''

655 _xlat(lat, _0_0, AlbersEqualAreaCylindrical)

656 _AlbersBase.__init__(self, _0_0, _1_0, _0_0, _1_0, 1, datum, **name)

657

658

659 class AlbersEqualAreaNorth(_AlbersBase):

660 '''An azimuthal L{AlbersEqualArea} projection at C{lat=90} and C{k0=1}

661 degenerating to the L{azimuthal} L{LambertEqualArea} projection.

662 '''

663 _lat1 = _lat2 = _Lat(lat1=_90_0)

664

665 def __init__(self, lat=_90_0, datum=_WGS84, **name):

666 '''New L{AlbersEqualAreaNorth} projection.

667

668 @kwarg lat: Standard parallel (C{90 degrees} I{fixed}).

669 @kwarg datum: Optional datum or ellipsoid (L{Datum}, L{Ellipsoid},

670 L{Ellipsoid2} or L{a_f2Tuple}).

671 @kwarg name: Optional C{B{name}=NN} for the projection (C{str}).

672 '''

673 _xlat(lat, _90_0, AlbersEqualAreaNorth)

674 _AlbersBase.__init__(self, _1_0, _0_0, _1_0, _0_0, 1, datum, **name)

675

676

677 class AlbersEqualAreaSouth(_AlbersBase):

678 '''An azimuthal L{AlbersEqualArea} projection at C{lat=-90} and C{k0=1}

679 degenerating to the L{azimuthal} L{LambertEqualArea} projection.

680 '''

681 _lat1 = _lat2 = _Lat(lat1=_N_90_0)

682

683 def __init__(self, lat=_N_90_0, datum=_WGS84, **name):

684 '''New L{AlbersEqualAreaSouth} projection.

685

686 @kwarg lat: Standard parallel (C{-90 degrees} I{fixed}).

687 @kwarg datum: Optional datum or ellipsoid (L{Datum}, L{Ellipsoid},

688 L{Ellipsoid2} or L{a_f2Tuple}).

689 @kwarg name: Optional C{B{name}=NN} for the projection (C{str}).

690 '''

691 _xlat(lat, _N_90_0, AlbersEqualAreaSouth)

692 _AlbersBase.__init__(self, _N_1_0, _0_0, _N_1_0, _0_0, 1, datum, **name)

693

694

695 class Albers7Tuple(_NamedTuple):

696 '''7-Tuple C{(x, y, lat, lon, gamma, scale, datum)}, in C{meter},

697 C{meter}, C{degrees90}, C{degrees180}, C{degrees360}, C{scalar} and

698 C{Datum} where C{(x, y)} is the projected, C{(lat, lon)} the geodetic

699 location, C{gamma} the meridian convergence at point, the bearing of

700 the y-axis measured clockwise from true North and C{scale} is the

701 azimuthal scale of the projection at point. The radial scale is

702 the reciprocal C{1 / scale}.

703 '''

704 _Names_ = (_x_, _y_, _lat_, _lon_, _gamma_, _scale_, _datum_)

705 _Units_ = ( Meter, Meter, Lat, Lon, Bearing, _Pass, _Pass)

706

707

708 def _atanh1(x):

709 '''(INTERNAL) Function M{atanh(sqrt(x)) / sqrt(x) - 1}.

710 '''

711 s = fabs(x)

712 if 0 < s < _0_5: # for typical ...

713 # x < E.e^2 == 2 * E.f use ...

714 # x / 3 + x^2 / 5 + x^3 / 7 + ...

715 y, k = x, 3

716 _S2 = Fsum(y / k).fsum2f_

717 for _ in range(_TERMS): # 9 terms

718 y *= x # x**n

719 k += 2 # 2*n + 1

720 s, d = _S2(y / k)

721 if not d:

722 break

723 elif s:

724 s = sqrt(s)

725 s = (atanh(s) if x > 0 else atan1(s)) / s - _1_0

726 return s

727

728

729 def _atanheE(x, E): # see Ellipsoid._es_atanh, .AuxLat._atanhee

730 '''(INTERNAL) Function M{atanhee(x)}, defined as ...

731 atanh( E.e * x) / E.e if f > 0 # oblate

732 atan (sqrt(-E.e2) * x) / sqrt(-E.e2) if f < 0 # prolate

733 x if f = 0.

734 '''

735 e = E.e # == sqrt(E.e2abs)

736 if e and x:

737 if E.f > 0: # .isOblate

738 x = atanh(x * e) / e

739 elif E.f < 0: # .isProlate

740 x = atan1(x * e) / e

741 return x

742

743

744 def _DatanheE(x, y, E): # see .rhumb.ekx._DeatanhE

745 '''(INTERNAL) Function M{Datanhee(x, y)}, defined as

746 M{atanhee((x - y) / (1 - E.e^2 * x * y)) / (x - y)}.

747 '''

748 e = _1_0 - E.e2 * x * y

749 if e:

750 d = x - y

751 e = (_atanheE(d / e, E) / d) if d else (_1_0 / e)

752 return e

753

754

755 def _D2atanheE(x, y, E):

756 '''(INTERNAL) Function M{D2atanhee(x, y)}, defined as

757 M{(Datanhee(1, y) - Datanhee(1, x)) / (y - x)}.

758 '''

759 s, e2 = _0_0, E.e2

760 if e2:

761 if ((fabs(x) + fabs(y)) * e2) < _0_5:

762 e = z = _1_0

763 k = 1

764 T = Fsum() # Taylor expansion

765 _T = T.Fsumf_

766 _C = Fsum().Fsum_

767 _S2 = Fsum().fsum2_

768 for _ in range(_TERMS): # 15 terms

769 T *= y; P = _T(z); z *= x # PYCHOK ;

770 T *= y; Q = _T(z); z *= x # PYCHOK ;

771 e *= e2

772 k += 2

773 s, d = _S2(_C(P, Q) * e / k)

774 if not d:

775 break

776 else: # PYCHOK no cover

777 s = _1_0 - x

778 if s:

779 s = (_DatanheE(_1_0, y, E) - _DatanheE(x, y, E)) / s

780 return s

781

782

783 def _Dsn(x, y, sx, sy):

784 '''(INTERNAL) Divided differences, defined as M{Df(x, y) = (f(x) - f(y)) / (x - y)}

785 with M{sn(x) = x / sqrt(1 + x^2)}: M{Dsn(x, y) = (x + y) / ((sn(x) + sn(y)) *

786 (1 + x^2) * (1 + y^2))}.

787

788 @see: U{W. M. Kahan and R. J. Fateman, "Sympbolic Computation of Divided

789 Differences"<https://People.EECS.Berkeley.EDU/~fateman/papers/divdiff.pdf>},

790 U{ACM SIGSAM Bulletin 33(2), 7-28 (1999)<https://DOI.org/10.1145/334714.334716>}

791 and U{AlbersEqualArea.hpp

792 <https://GeographicLib.SourceForge.io/C++/doc/AlbersEqualArea_8hpp_source.html>}.

793 '''

794 # sx = x / hypot1(x)

795 d, t = _1_0, (x * y)

796 if t > 0:

797 s = sx + sy

798 if s:

799 t = sx * sy / t

800 d = t**2 * (x + y) / s

801 elif x != y:

802 d = (sx - sy) / (x - y)

803 return d

804

805

806 def _tol(tol, x):

807 '''(INTERNAL) Converge tolerance.

808 '''

809 return tol * max(_1_0, fabs(x))

810

811

812 def _1_x21(x):

813 '''(INTERNAL) Return M{1 / (x**2 + 1)}.

814 '''

815 return _1_0 / (x**2 + _1_0)

816

817

818 def _xlat(lat, f, where):

819 '''(INTERNAL) check fixed C{lat}.

820 '''

821 if lat is not f and _Lat(lat=lat) != f:

822 t = unstr(where, lat=lat)

823 raise AlbersError(t, txt_not_=f)

824

825

826__all__ += _ALL_DOCS(_AlbersBase)

827

828# **) MIT License

829#

830# Copyright (C) 2016-2025 -- mrJean1 at Gmail -- All Rights Reserved.

831#

832# Permission is hereby granted, free of charge, to any person obtaining a

833# copy of this software and associated documentation files (the "Software"),

834# to deal in the Software without restriction, including without limitation

835# the rights to use, copy, modify, merge, publish, distribute, sublicense,

836# and/or sell copies of the Software, and to permit persons to whom the

837# Software is furnished to do so, subject to the following conditions:

838#

839# The above copyright notice and this permission notice shall be included

840# in all copies or substantial portions of the Software.

841#

842# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

843# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

844# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

845# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR

846# OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,

847# ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR

848# OTHER DEALINGS IN THE SOFTWARE.