def initialBearingTo(self, other, wrap=False):
'''Compute the initial bearing (aka forward azimuth) from
this to an other point.
@param other: The other point (L{LatLon}).
@keyword wrap: Wrap and unroll longitudes (bool).
@return: Initial bearing (compass degrees).
@raise TypeError: The I{other} point is not L{LatLon}.
@example:
>>> p1 = LatLon(52.205, 0.119)
>>> p2 = LatLon(48.857, 2.351)
>>> b = p1.initialBearingTo(p2) # 156.2
@JSname: I{bearingTo}.
'''
self.others(other)
a1, b1 = self.to2ab()
a2, b2 = other.to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
ca1, ca2, cdb = map1(cos, a1, a2, db)
sa1, sa2, sdb = map1(sin, a1, a2, db)
# see <http://mathforum.org/library/drmath/view/55417.html>
x = ca1 * sa2 - sa1 * ca2 * cdb
y = sdb * ca2
return degrees360(atan2(y, x))
def distanceTo(self, other, radius=R_M, wrap=False):
'''Compute the distance from this to an other point.
@param other: The other point (L{LatLon}).
@keyword radius: Optional, mean earth radius (meter).
@keyword wrap: Wrap and unroll longitudes (bool).
@return: Distance between this and the I{other} point
(in the same units as radius).
@raise TypeError: The I{other} point is not L{LatLon}.
@example:
>>> p1 = LatLon(52.205, 0.119)
>>> p2 = LatLon(48.857, 2.351);
>>> d = p1.distanceTo(p2) # 404300
'''
self.others(other)
a1, b1 = self.to2ab()
a2, b2 = other.to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
r = haversine_(a2, a1, db)
return r * float(radius)
def crossingParallels(self, other, lat, wrap=False):
'''Return the pair of meridians at which a great circle defined
by this and an other point crosses the given latitude.
@param other: The other point defining great circle (L{LatLon}).
@param lat: Latitude at the crossing (degrees).
@keyword wrap: Wrap and unroll longitudes (bool).
@return: 2-Tuple (lon1, lon2) in (degrees180) or None if the
great circle doesn't reach the given I{lat}.
'''
self.others(other)
a1, b1 = self.to2ab()
a2, b2 = other.to2ab()
a = radians(lat)
db, b2 = unrollPI(b1, b2, wrap=wrap)
ca, ca1, ca2, cdb = map1(cos, a, a1, a2, db)
sa, sa1, sa2, sdb = map1(sin, a, a1, a2, db)
x = sa1 * ca2 * ca * sdb
y = sa1 * ca2 * ca * cdb - ca1 * sa2 * ca
z = ca1 * ca2 * sa * sdb
h = hypot(x, y)
if h < EPS or abs(z) > h:
return None # great circle doesn't reach latitude
m = atan2(-y, x) + b1 # longitude at max latitude
d = acos(z / h) # delta longitude to intersections
return degrees180(m - d), degrees180(m + d)
def _exs(n, points): # iterate over spherical edge excess
a1, b1 = points[n - 1].to2ab()
ta1 = tan_2(a1)
for i in range(n):
a2, b2 = points[i].to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
ta2, tdb = map1(tan_2, a2, db)
yield atan2(tdb * (ta1 + ta2), 1 + ta1 * ta2)
ta1, b1 = ta2, b2
def _rads(n, points, closed): # angular edge lengths in radians
if closed:
m, i = 0, n - 1
else:
m, i = 1, 0
a1, b1 = points[i].to2ab()
for i in range(m, n):
a2, b2 = points[i].to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
yield haversine_(a2, a1, db)
a1, b1 = a2, b2
def intermediateTo(self, other, fraction, height=None, wrap=False):
'''Locate the point at given fraction between this and an
other point.
@param other: The other point (L{LatLon}).
@param fraction: Fraction between both points (float, 0.0 =
this point, 1.0 = the other point).
@keyword height: Optional height, overriding the fractional
height (meter).
@keyword wrap: Wrap and unroll longitudes (bool).
@return: Intermediate point (L{LatLon}).
@raise TypeError: The I{other} point is not L{LatLon}.
@example:
>>> p1 = LatLon(52.205, 0.119)
>>> p2 = LatLon(48.857, 2.351)
>>> p = p1.intermediateTo(p2, 0.25) # 51.3721°N, 000.7073°E
@JSname: I{intermediatePointTo}.
'''
self.others(other)
a1, b1 = self.to2ab()
a2, b2 = other.to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
r = haversine_(a2, a1, db)
if r > EPS:
cb1, cb2, ca1, ca2 = map1(cos, b1, b2, a1, a2)
sb1, sb2, sa1, sa2, sr = map1(sin, b1, b2, a1, a2, r)
A = sin((1 - fraction) * r) / sr
B = sin(fraction * r) / sr
x = A * ca1 * cb1 + B * ca2 * cb2
y = A * ca1 * sb1 + B * ca2 * sb2
z = A * sa1 + B * sa2
a = atan2(z, hypot(x, y))
b = atan2(y, x)
else: # points too close
a = favg(a1, a2, f=fraction)
b = favg(b1, b2, f=fraction)
if height is None:
h = self._havg(other, f=fraction)
else:
h = height
return self.classof(degrees90(a), degrees180(b), height=h)
def _rads2(n, pts): # trapezoidal areas in rads**2
x1, y1, _ = pts[n - 1]
for i in range(n):
x2, y2, _ = pts[i]
w, x2 = unrollPI(x1, x2, wrap=wrap)
# approximate trapezoid by a rectangle, adjusting
# the top width by the cosine of the latitudinal
# average and bottom width by some fudge factor
h = (y2 + y1) * 0.5
if adjust:
w *= (cos(h) + 1.2876) * 0.5
yield h * w # signed trapezoidal area
x1, y1 = x2, y2
def distance3(self, other, radius=R_M, wrap=False):
'''Compute the great-circle distance between this and an other
geohash using the U{Haversine
<http://www.movable-type.co.uk/scripts/latlong.html>} formula.
@param other: The other geohash (L{Geohash}).
@keyword radius: Optional, mean earth radius (meter).
@keyword wrap: Wrap and unroll longitudes (bool).
@return: Great-circle distance (meter, same units as I{radius}).
@raise TypeError: The I{other} is not a L{Geohash}, I{LatLon}
or str.
'''
other = _2Geohash(other)
a1, b1 = self.ab
a2, b2 = other.ab
db, b2 = unrollPI(b1, b2, wrap=wrap)
return haversine_(a2, a1, db) * float(radius)
def midpointTo(self, other, height=None, wrap=False):
'''Find the midpoint between this and an other point.
@param other: The other point (L{LatLon}).
@keyword height: Optional height for midpoint, overriding
the mean height (meter).
@keyword wrap: Wrap and unroll longitudes (bool).
@return: Midpoint (L{LatLon}).
@raise TypeError: The I{other} point is not L{LatLon}.
@example:
>>> p1 = LatLon(52.205, 0.119)
>>> p2 = LatLon(48.857, 2.351)
>>> m = p1.midpointTo(p2) # '50.5363°N, 001.2746°E'
'''
self.others(other)
# see <http://mathforum.org/library/drmath/view/51822.html>
a1, b1 = self.to2ab()
a2, b2 = other.to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
ca1, ca2, cdb = map1(cos, a1, a2, db)
sa1, sa2, sdb = map1(sin, a1, a2, db)
x = ca2 * cdb + ca1
y = ca2 * sdb
a = atan2(sa1 + sa2, hypot(x, y))
b = atan2(y, x) + b1
if height is None:
h = self._havg(other)
else:
h = height
return self.classof(degrees90(a), degrees180(b), height=h)
def intersection(start1,
bearing1,
start2,
bearing2,
height=None,
wrap=False,
LatLon=LatLon):
'''Compute the intersection point of two paths each defined
by a start point and an initial bearing.
@param start1: Start point of first path (L{LatLon}).
@param bearing1: Initial bearing from start1 (compass degrees).
@param start2: Start point of second path (L{LatLon}).
@param bearing2: Initial bearing from start2 (compass degrees).
@keyword height: Optional height for the intersection point,
overriding the mean height (meter).
@keyword wrap: Wrap and unroll longitudes (bool).
@keyword LatLon: Optional LatLon class for the intersection
point (L{LatLon}) or None.
@return: Intersection point (L{LatLon}) or 3-tuple
(lat, lon, height) if I{LatLon} is None.
@raise TypeError: Point I{start1} or I{start2} is not L{LatLon}.
@raise ValueError: Intersection is ambiguous or infinite
or the paths are parallel or coincide.
@example:
>>> p = LatLon(51.8853, 0.2545)
>>> s = LatLon(49.0034, 2.5735)
>>> i = intersection(p, 108.547, s, 32.435) # '50.9078°N, 004.5084°E'
'''
_Trll.others(start1, name='start1')
_Trll.others(start2, name='start2')
# see <http://www.edwilliams.org/avform.htm#Intersection>
a1, b1 = start1.to2ab()
a2, b2 = start2.to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
r12 = haversine_(a2, a1, db)
if abs(r12) < EPS:
raise ValueError('intersection %s: %r vs %r' %
('parallel', start1, start2))
ca1, ca2 = map1(cos, a1, a2)
sa1, sa2, sr12 = map1(sin, a1, a2, r12)
x1, x2 = (sr12 * ca1), (sr12 * ca2)
if min(abs(x1), abs(x2)) < EPS:
raise ValueError('intersection %s: %r vs %r' %
('parallel', start1, start2))
cr12 = cos(r12)
t1, t2 = map1(acos, (sa2 - sa1 * cr12) / x1, (sa1 - sa2 * cr12) / x2)
if sin(db) > 0:
t12, t21 = t1, PI2 - t2
else:
t12, t21 = PI2 - t1, t2
t13, t23 = map1(radians, bearing1, bearing2)
x1, x2 = map1(
wrapPI,
t13 - t12, # angle 2-1-3
t21 - t23) # angle 1-2-3
sx1, sx2 = map1(sin, x1, x2)
if sx1 == 0 and sx2 == 0:
raise ValueError('intersection %s: %r vs %r' %
('infinite', start1, start2))
sx3 = sx1 * sx2
if sx3 < 0:
raise ValueError('intersection %s: %r vs %r' %
('ambiguous', start1, start2))
cx1, cx2 = map1(cos, x1, x2)
x3 = acos(cr12 * sx3 - cx2 * cx1)
r13 = atan2(sr12 * sx3, cx2 + cx1 * cos(x3))
a, b = _destination2(a1, b1, r13, t13)
h = start1._havg(start2) if height is None else height
return (a, b, h) if LatLon is None else LatLon(a, b, height=h)
def areaOf(points, radius=R_M, wrap=True):
'''Calculate the area of a spherical polygon where the sides
of the polygon are great circle arcs joining the points.
@param points: The points defining the polygon (L{LatLon}[]).
@keyword radius: Optional, mean earth radius (meter).
@keyword wrap: Wrap and unroll longitudes (bool).
@return: Polygon area (float, same units as radius squared).
@raise TypeError: Some I{points} are not L{LatLon}.
@raise ValueError: Insufficient number of I{points}.
@note: The area is based on Karney U{'Area of a spherical polygon'
<http://osgeo-org.1560.x6.nabble.com/Area-of-a-spherical-polygon-td3841625.html>}.
@see: L{pygeodesy.areaOf}, L{sphericalNvector.areaOf} and
L{ellipsoidalVincenty.areaOf}.
@example:
>>> b = LatLon(45, 1), LatLon(45, 2), LatLon(46, 2), LatLon(46, 1)
>>> areaOf(b) # 8666058750.718977
>>> c = LatLon(0, 0), LatLon(1, 0), LatLon(0, 1)
>>> areaOf(c) # 6.18e9
'''
n, points = _Trll.points(points, closed=True)
# Area method due to Karney: for each edge of the polygon,
#
# tan(Δλ/2) · (tan(φ1/2) + tan(φ2/2))
# tan(E/2) = ------------------------------------
# 1 + tan(φ1/2) · tan(φ2/2)
#
# where E is the spherical excess of the trapezium obtained by
# extending the edge to the equator-circle vector for each edge
if iterNumpy2(points):
def _exs(n, points): # iterate over spherical edge excess
a1, b1 = points[n - 1].to2ab()
ta1 = tan_2(a1)
for i in range(n):
a2, b2 = points[i].to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
ta2, tdb = map1(tan_2, a2, db)
yield atan2(tdb * (ta1 + ta2), 1 + ta1 * ta2)
ta1, b1 = ta2, b2
s = fsum(_exs(n, points)) * 2
else:
a1, b1 = points[n - 1].to2ab()
s, ta1 = [], tan_2(a1)
for i in range(n):
a2, b2 = points[i].to2ab()
db, b2 = unrollPI(b1, b2, wrap=wrap)
ta2, tdb = map1(tan_2, a2, db)
s.append(atan2(tdb * (ta1 + ta2), 1 + ta1 * ta2))
ta1, b1 = ta2, b2
s = fsum(s) * 2
if isPoleEnclosedBy(points):
s = abs(s) - PI2
return abs(s * radius**2)