def parseMGRS(strMGRS, datum=Datums.WGS84, Mgrs=Mgrs, name=''):
'''Parse a string representing a MGRS grid reference,
consisting of zoneBand, grid, easting and northing.
@param strMGRS: MGRS grid reference (C{str}).
@keyword datum: Optional datum to use (L{Datum}).
@keyword Mgrs: Optional (sub-)class to return the MGRS
grid reference (L{Mgrs}) or C{None}.
@keyword name: Optional B{C{Mgrs}} name (C{str}).
@return: The MGRS grid reference (B{L{Mgrs}}) or an
L{Mgrs4Tuple}C{(zone, digraph, easting, northing)}
if B{C{Mgrs}} is C{None}.
@raise ValueError: Invalid B{C{strMGRS}}.
@example:
>>> m = parseMGRS('31U DQ 48251 11932')
>>> str(m) # 31U DQ 48251 11932
>>> m = parseMGRS('31UDQ4825111932')
>>> repr(m) # [Z:31U, G:DQ, E:48251, N:11932]
'''
def _mg(cre, s): # return re.match groups
m = cre.match(s)
if not m:
raise ValueError
return m.groups()
def _s2m(g): # e or n string to meter
f = float(g)
if f > 0:
x = int(log10(f))
if 0 <= x < 4: # at least 5 digits
f *= (10000, 1000, 100, 10)[x]
return f
m = tuple(strMGRS.strip().replace(',', ' ').split())
try:
if len(m) == 1: # 01ABC1234512345'
m = _mg(_MGRSre, m[0])
m = m[:2] + halfs2(m[2])
elif len(m) == 2: # 01ABC 1234512345'
m = _mg(_GZDre, m[0]) + halfs2(m[1])
elif len(m) == 3: # 01ABC 12345 12345'
m = _mg(_GZDre, m[0]) + m[1:]
if len(m) != 4: # 01A BC 1234 12345
raise ValueError
e, n = map(_s2m, m[2:])
except ValueError:
raise ValueError('%s invalid: %r' % ('strMGRS', strMGRS))
z, EN = m[0], m[1].upper()
r = Mgrs4Tuple(z, EN, e, n) if Mgrs is None else \
Mgrs(z, EN, e, n, datum=datum)
return _xnamed(r, name)
def parseOSGR(strOSGR, Osgr=Osgr, name=''):
'''Parse an OSGR coordinate string to an Osgr instance.
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 metres, for
example '438700,114800'.
@param strOSGR: An OSGR coordinate (C{str}).
@keyword Osgr: Optional (sub-)class to return the OSGR
coordinate (L{Osgr}) or C{None}.
@keyword name: Optional I{Osgr} name (C{str}).
@return: The OSGR coordinate (L{Osgr}) or the 2-tuple
(easting, northing) if I{Osgr} is C{None}.
@raise ValueError: Invalid I{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):
g += '00000' # std to meter
return int(str(G) + g[:5])
s = strOSGR.strip()
try:
g = s.split(',')
if len(g) == 2: # "easting,northing"
if len(s) < 13:
raise ValueError # caught below
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 # caught below
g = s.split()
if len(g) == 1: # no whitespace
e, n = halfs2(s)
elif len(g) == 2:
e, n = g
else:
raise ValueError # caught below
e = _s2i(E, e)
n = _s2i(N, n)
except ValueError:
raise ValueError('%s invalid: %r' % ('strOSGR', strOSGR))
return (e, n) if Osgr is None else _xnamed(Osgr(e, n), name)