# Coverage for pygeodesy/osgr.py : 94%

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Pure Python implementation of OS Grid Reference functions using an ellipsoidal earth model, transcribed from JavaScript originals by I{(C) Chris Veness 2005-2016} published under the same MIT Licence**, see U{OS National Grid<https://www.Movable-Type.co.UK/scripts/latlong-os-gridref.html>} and U{Module osgridref <https://www.Movable-Type.co.UK/scripts/geodesy/docs/module-osgridref.html>}. OSGR provides geocoordinate references for UK mapping purposes, converted in 2015 to work with WGS84 datum by default or OSGB36 as option. See U{Guide<https://www.OrdnanceSurvey.co.UK/docs/support/guide-coordinate-systems-great-britain.pdf>}, U{Proposed Changes<https://www.OrdnanceSurvey.co.UK/blog/2014/09/proposed-changes-to-latitude-and-longitude-representation-on-paper-maps-tell-us-your-thoughts>}, U{Confirmation<https://www.OrdnanceSurvey.co.UK/blog/2014/12/confirmation-on-changes-to-latitude-and-longitude>} and U{Ordnance Survey National Grid<https://WikiPedia.org/wiki/Ordnance_Survey_National_Grid>}. See also Karney U{'Transverse Mercator with an accuracy of a few nanometers' <https://Arxiv.org/pdf/1002.1417v3.pdf>}, 2011 (building on Krüger U{'Konforme Abbildung des Erdellipsoids in der Ebene' <https://bib.GFZ-Potsdam.DE/pub/digi/krueger2.pdf>}, 1912), Seidel U{'Die Mathematik der Gauß-Krueger-Abbildung' <https://Henrik-Seidel.GMXhome.DE/gausskrueger.pdf>}, 2006 and U{Transverse Mercator: Redfearn series <https://WikiPedia.org/wiki/Transverse_Mercator:_Redfearn_series>}. @newfield example: Example, Examples ''' # make sure int/int division yields float quotient from __future__ import division division = 1 / 2 # double check int division, see .datum.py, .utily.py if not division: raise ImportError('%s 1/2 == %d' % ('division', division)) del division from pygeodesy.basics import halfs2, map1, property_RO, \ _xsubclassof, _xzipairs from pygeodesy.datums import Datums, _ellipsoidal_datum from pygeodesy.dms import parseDMS2 from pygeodesy.ellipsoidalBase import LatLonEllipsoidalBase as _LLEB from pygeodesy.errors import _parseX, _TypeError, _ValueError from pygeodesy.fmath import fdot, fpowers, Fsum, fsum_ from pygeodesy.interns import NN, _COLON_, _COMMA_, _COMMA_SPACE_, \ _dot_, _item_ps, _no_convergence_, \ _SPACE_, _SQUARE_, _1_0 from pygeodesy.lazily import _ALL_LAZY from pygeodesy.named import _NamedBase, nameof, _xnamed from pygeodesy.namedTuples import EasNor2Tuple, LatLonDatum3Tuple from pygeodesy.streprs import enstr2 from pygeodesy.units import Easting, Lam_, Northing, Phi_, Scalar from pygeodesy.utily import degrees90, degrees180, sincos2 from math import cos, radians, sin, sqrt, tan __all__ = _ALL_LAZY.osgr __version__ = '20.09.22' _10um = 1e-5 # 0.01 millimeter (C{meter}) _100km = 100000 # 100 km (int meter) _A0 = Phi_(49) # NatGrid true origin latitude, 49°N _B0 = Lam_(-2) # NatGrid true origin longitude, 2°W _E0 = Easting(400e3) # Easting of true origin (C{meter}) _N0 = Northing(-100e3) # Northing of true origin (C{meter}) _F0 = Scalar(0.9996012717) # NatGrid scale of central meridian (C{float}) _Datums_OSGB36 = Datums.OSGB36 # Airy130 ellipsoid _latlon_ = 'latlon' _no_convertDatum_ = 'no .convertDatum' _ord_A = ord('A') _TRIPS = 33 # .toLatLon convergence def _ll2datum(ll, datum, name): '''(INTERNAL) Convert datum if needed. ''' if datum not in (None, ll.datum): try: ll = ll.convertDatum(datum) except AttributeError: raise _TypeError(name, ll, txt=_item_ps(_no_convertDatum_, datum.name)) return ll def _M(Mabcd, a): '''(INTERNAL) Compute meridional arc. ''' a_ = a - _A0 _a = a + _A0 return fdot(Mabcd, a_, -sin(a_) * cos(_a), sin(a_ * 2) * cos(_a * 2), -sin(a_ * 3) * cos(_a * 3)) class OSGRError(_ValueError): '''Ordinance Survey Grid References (OSGR) parse or other L{Osgr} issue. ''' pass class Osgr(_NamedBase): '''Ordinance Survey Grid References (OSGR) coordinate. ''' _datum = _Datums_OSGB36 # default datum (L{Datum}) _easting = 0 # Easting (C{meter}) _iteration = 0 # iteration number (C{int}) _latlon = None # cached B{C{_toLatlon}} _northing = 0 # Nothing (C{meter}) def __init__(self, easting, northing, datum=None, name=NN): '''New L{Osgr} National Grid Reference. @arg easting: Easting from OS false easting (C{meter}). @arg northing: Northing from from OS false northing (C{meter}). @kwarg datum: Default datum (C{Datums.OSGB36}). @kwarg name: Optional name (C{str}). @raise OSGRError: Invalid or negative B{C{easting}} or B{C{northing}} or B{C{datum}} not C{Datums.OSBG36}. @example: >>> from pygeodesy import Osgr >>> r = Osgr(651409, 313177) ''' self._easting = Easting( easting, Error=OSGRError, osgr=True) self._northing = Northing(northing, Error=OSGRError, osgr=True) if datum not in (None, _Datums_OSGB36): try: if _ellipsoidal_datum(datum) != _Datums_OSGB36: raise ValueError except (TypeError, ValueError): raise OSGRError(datum=datum) if name: self.name = name @property_RO def datum(self): '''Get the datum (L{Datum}). ''' return self._datum @property_RO def easting(self): '''Get the easting (C{meter}). ''' return self._easting @property_RO def iteration(self): '''Get the most recent C{Osgr.toLatLon} iteration number (C{int} or C{0} if not available/applicable). ''' return self._iteration @property_RO def northing(self): '''Get the northing (C{meter}). ''' return self._northing def parse(self, strOSGR, name=NN): '''Parse a string to a similar L{Osgr} instance. @arg strOSGR: The OSGR reference (C{str}), see function L{parseOSGR}. @kwarg name: Optional instance name (C{str}), overriding this name. @return: The similar instance (L{Osgr}) @raise OSGRError: Invalid B{C{strOSGR}}. ''' return parseOSGR(strOSGR, Osgr=self.classof, name=name or self.name) def toLatLon(self, LatLon=None, datum=Datums.WGS84): '''Convert this OSGR coordinate to an (ellipsoidal) geodetic point. While OS grid references are based on the OSGB36 datum, the I{Ordnance Survey} have deprecated the use of OSGB36 for lat-/longitude coordinates (in favour of WGS84). Hence, this method returns WGS84 by default with OSGB36 as an option, U{see<https://www.OrdnanceSurvey.co.UK/blog/2014/12/2>}. I{Note formulation implemented here due to Thomas, Redfearn, etc. is as published by OS, but is inferior to Krüger as used by e.g. Karney 2011.} @kwarg LatLon: Optional ellipsoidal class to return the geodetic point (C{LatLon}) or C{None}. @kwarg datum: Optional datum to convert to (L{Datum}, L{Ellipsoid}, L{Ellipsoid2}, L{Ellipsoid2} or L{a_f2Tuple}). @return: The geodetic point (B{C{LatLon}}) or a L{LatLonDatum3Tuple}C{(lat, lon, datum)} if B{C{LatLon}} is C{None}. @raise OSGRError: No convergence. @raise TypeError: If B{C{LatLon}} is not ellipsoidal or B{C{datum}} is invalid or conversion failed. @example: >>> from pygeodesy import ellipsoidalVincenty as eV >>> g = Osgr(651409.903, 313177.270) >>> p = g.toLatLon(eV.LatLon) # 52°39′28.723″N, 001°42′57.787″E >>> # to obtain (historical) OSGB36 lat-/longitude point >>> p = g.toLatLon(eV.LatLon, datum=Datums.OSGB36) # 52°39′27.253″N, 001°43′04.518″E ''' if self._latlon: return self._latlon3(LatLon, datum) E = self.datum.ellipsoid # _Datums_OSGB36.ellipsoid, Airy130 a_F0 = E.a * _F0 b_F0 = E.b * _F0 e, n = self.easting, self.northing n_N0 = n - _N0 a, m = _A0, n_N0 sa = Fsum(a) for self._iteration in range(1, _TRIPS): a = sa.fsum_(m / a_F0) m = n_N0 - b_F0 * _M(E.Mabcd, a) # meridional arc if abs(m) < _10um: break else: t = _dot_(_item_ps(self.classname, self.toStr(prec=-3)), self.toLatLon.__name__) raise OSGRError(_no_convergence_, txt=t) sa, ca = sincos2(a) s = E.e2s2(sa) # r, v = E.roc2_(sa, _F0) v = a_F0 / sqrt(s) # nu r = v * E.e12 / s # rho = a_F0 * E.e12 / pow(s, 1.5) == a_F0 * E.e12 / (s * sqrt(s)) vr = v / r # == s / E.e12 x2 = vr - _1_0 # η2 ta = tan(a) v3, v5, v7 = fpowers(v, 7, 3) # PYCHOK false! ta2, ta4, ta6 = fpowers(ta**2, 3) # PYCHOK false! tar = ta / r V4 = (a, tar / ( 2 * v), tar / ( 24 * v3) * fdot((1, 3, -9), 5 + x2, ta2, ta2 * x2), tar / (720 * v5) * fdot((61, 90, 45), _1_0, ta2, ta4)) csa = _1_0 / ca X5 = (_B0, csa / v, csa / ( 6 * v3) * fsum_(vr, ta2, ta2), csa / ( 120 * v5) * fdot((5, 28, 24), _1_0, ta2, ta4), csa / (5040 * v7) * fdot((61, 662, 1320, 720), _1_0, ta2, ta4, ta6)) d, d2, d3, d4, d5, d6, d7 = fpowers(e - _E0, 7) # PYCHOK false! a = fdot(V4, _1_0, -d2, d4, -d6) b = fdot(X5, _1_0, d, -d3, d5, -d7) r = _LLEB(degrees90(a), degrees180(b), datum=self.datum, name=self.name) r._iteration = self._iteration # only ellipsoidal LatLon self._latlon = r return self._latlon3(LatLon, datum) def _latlon3(self, LatLon, datum): '''(INTERNAL) Convert cached latlon to C{LatLon} ''' ll = self._latlon if LatLon is None: r = _ll2datum(ll, datum, LatLonDatum3Tuple.__name__) r = LatLonDatum3Tuple(r.lat, r.lon, r.datum) else: # must be ellipsoidal _xsubclassof(_LLEB, LatLon=LatLon) r = _ll2datum(ll, datum, LatLon.__name__) r = LatLon(r.lat, r.lon, datum=r.datum) r._iteration = ll._iteration return _xnamed(r, ll) def toRepr(self, prec=10, fmt=_SQUARE_, sep=_COMMA_SPACE_): # PYCHOK expected '''Return a string representation of this OSGR coordinate. @kwarg prec: Optional number of digits (C{int}). @kwarg fmt: Optional enclosing backets format (C{str}). @kwarg sep: Optional separator to join (C{str}). @return: This OSGR (C{str}) "[G:00B, E:meter, N:meter]" or "[OSGR:meter,meter]" if B{C{prec}} is non-positive. ''' t = self.toStr(prec=prec, sep=None) return _xzipairs('GEN', t, sep=sep, fmt=fmt) if prec > 0 else \ (fmt % (_COLON_.join((Osgr.__name__.upper(), t)),)) toStr2 = toRepr # PYCHOK for backward compatibility '''DEPRECATED, use method L{Osgr.toRepr}.''' def toStr(self, prec=10, sep=_SPACE_): # PYCHOK expected '''Return a string representation of this OSGR coordinate. Note that OSGR coordinates are truncated, not rounded (unlike UTM grid references). @kwarg prec: Optional number of digits (C{int}). @kwarg sep: Optional C{join} separator (C{str}) or C{None} to return an unjoined C{tuple} of C{str}s. @return: This OSGR as C{"EN easting northing"} or as C{"easting,northing"} if B{C{prec}} is non-positive (C{str}). @raise ValueError: Invalid B{C{prec}}. @example: >>> r = Osgr(651409, 313177) >>> str(r) # TG 5140 1317 >>> r.toStr(prec=0) # 651409,313177 ''' def _i2c(i): if i > 7: i += 1 return chr(_ord_A + i) e, n, s = self._easting, self._northing, _COMMA_ if prec > 0: E, e = divmod(e, _100km) N, n = divmod(n, _100km) E, N = int(E), int(N) if 0 > E or E > 6 or \ 0 > N or N > 12: return NN N = 19 - N EN = _i2c( N - (N % 5) + (E + 10) // 5) + \ _i2c((N * 5) % 25 + (E % 5)) t = enstr2(e, n, prec, EN) s = sep elif -6 < prec < 0: w = 6 + 1 - prec t = ['%0*.*f' % (w, -prec, t) for t in (e, n)] else: t = ['%06d' % int(t) for t in (e, n)] return tuple(t) if s is None else s.join(t) def parseOSGR(strOSGR, Osgr=Osgr, name=NN): '''Parse a string representing an OSGR grid reference, consisting of C{"[grid] easting northing"}. Accepts standard OS Grid References like 'SU 387 148', with or without whitespace separators, from 2- up to 10-digit references (1 m × 1 m square), or fully numeric, comma-separated references in meters, for example '438700,114800'. @arg strOSGR: An OSGR coordinate (C{str}). @kwarg Osgr: Optional class to return the OSGR coordinate (L{Osgr}) or C{None}. @kwarg name: Optional B{C{Osgr}} name (C{str}). @return: The OSGR coordinate (B{C{Osgr}}) or an L{EasNor2Tuple}C{(easting, northing)} if B{C{Osgr}} is C{None}. @raise OSGRError: Invalid B{C{strOSGR}}. @example: >>> g = parseOSGR('TG 51409 13177') >>> str(g) # TG 51409 13177 >>> g = parseOSGR('TG5140913177') >>> str(g) # TG 51409 13177 >>> g = parseOSGR('TG51409 13177') >>> str(g) # TG 51409 13177 >>> g = parseOSGR('651409,313177') >>> str(g) # TG 51409 13177 >>> g.toStr(prec=0) # 651409,313177 ''' def _c2i(G): g = ord(G.upper()) - _ord_A if g > 7: g -= 1 return g def _s2f(g): return float(g.strip()) def _s2i(G, g): m = g + '00000' # std to meter return int(str(G) + m[:5]) def _OSGR_(strOSGR, Osgr, name): s = strOSGR.strip() g = s.split(_COMMA_) if len(g) == 2: # "easting,northing" if len(s) < 13: raise ValueError e, n = map(_s2f, g) else: # "GR easting northing" g, s = s[:2], s[2:].strip() e, n = map(_c2i, g) n, m = divmod(n, 5) E = ((e - 2) % 5) * 5 + m N = 19 - (e // 5) * 5 - n if 0 > E or E > 6 or \ 0 > N or N > 12: raise ValueError g = s.split() if len(g) == 1: # no whitespace e, n = halfs2(s) elif len(g) == 2: e, n = g else: raise ValueError e = _s2i(E, e) n = _s2i(N, n) r = EasNor2Tuple(e, n) if Osgr is None else Osgr(e, n) return _xnamed(r, name, force=True) return _parseX(_OSGR_, strOSGR, Osgr, name, strOSGR=strOSGR, Error=OSGRError) def toOsgr(latlon, lon=None, datum=Datums.WGS84, Osgr=Osgr, name=NN, **Osgr_kwds): '''Convert a lat-/longitude point to an OSGR coordinate. @arg latlon: Latitude (C{degrees}) or an (ellipsoidal) geodetic C{LatLon} point. @kwarg lon: Optional longitude in degrees (scalar or C{None}). @kwarg datum: Optional datum to convert B{C{lat, lon}} from (L{Datum}, L{Ellipsoid}, L{Ellipsoid2} or L{a_f2Tuple}). @kwarg Osgr: Optional class to return the OSGR coordinate (L{Osgr}) or C{None}. @kwarg name: Optional B{C{Osgr}} name (C{str}). @kwarg Osgr_kwds: Optional, additional B{C{Osgr}} keyword arguments, ignored if B{C{Osgr=None}}. @return: The OSGR coordinate (B{C{Osgr}}) or an L{EasNor2Tuple}C{(easting, northing)} if B{C{Osgr}} is C{None}. @raise OSGRError: Invalid B{C{latlon}} or B{C{lon}}. @raise TypeError: Non-ellipsoidal B{C{latlon}} or invalid B{C{datum}} or conversion failed. @example: >>> p = LatLon(52.65798, 1.71605) >>> r = toOsgr(p) # TG 51409 13177 >>> # for conversion of (historical) OSGB36 lat-/longitude: >>> r = toOsgr(52.65757, 1.71791, datum=Datums.OSGB36) ''' if not isinstance(latlon, _LLEB): # XXX fix failing _LLEB.convertDatum() latlon = _LLEB(*parseDMS2(latlon, lon), datum=datum) elif lon is not None: raise OSGRError(lon=lon, txt='not %s' % (None,)) elif not name: # use latlon.name name = nameof(latlon) # if necessary, convert to OSGB36 first ll = _ll2datum(latlon, _Datums_OSGB36, _latlon_) try: a, b = ll.philam except AttributeError: a, b = map1(radians, ll.lat, ll.lon) sa, ca = sincos2(a) E = _Datums_OSGB36.ellipsoid s = E.e2s2(sa) # r, v = E.roc2_(sa, _F0); r = v / r v = E.a * _F0 / sqrt(s) # nu r = s / E.e12 # nu / rho == v / (v * E.e12 / s) == s / E.e12 x2 = r - _1_0 # η2 ta = tan(a) ca3, ca5 = fpowers(ca, 5, 3) # PYCHOK false! ta2, ta4 = fpowers(ta, 4, 2) # PYCHOK false! vsa = v * sa I4 = (E.b * _F0 * _M(E.Mabcd, a) + _N0, (vsa / 2) * ca, (vsa / 24) * ca3 * fsum_(5, -ta2, 9 * x2), (vsa / 720) * ca5 * fsum_(61, ta4, -58 * ta2)) V4 = (_E0, (v * ca), (v / 6) * ca3 * (r - ta2), (v / 120) * ca5 * fdot((-18, 1, 14, -58), ta2, 5 + ta4, x2, ta2 * x2)) d, d2, d3, d4, d5, d6 = fpowers(b - _B0, 6) # PYCHOK false! n = fdot(I4, _1_0, d2, d4, d6) e = fdot(V4, _1_0, d, d3, d5) if Osgr is None: r = EasNor2Tuple(e, n) else: r = Osgr(e, n, datum=_Datums_OSGB36, **Osgr_kwds) if lon is None and isinstance(latlon, _LLEB): r._latlon = latlon # XXX weakref(latlon)? return _xnamed(r, name) # **) MIT License # # Copyright (C) 2016-2020 -- mrJean1 at Gmail -- All Rights Reserved. # # Permission is hereby granted, free of charge, to any person obtaining a # copy of this software and associated documentation files (the "Software"), # to deal in the Software without restriction, including without limitation # the rights to use, copy, modify, merge, publish, distribute, sublicense, # and/or sell copies of the Software, and to permit persons to whom the # Software is furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included # in all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS # OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL # THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR # OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, # ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR # OTHER DEALINGS IN THE SOFTWARE.