def discrete(self, points, fraction=None):
'''Compute only the C{forward Frechet} distance.
@param points: Second set of points (C{LatLon}[], C{Numpy2LatLon}[],
C{Tuple2LatLon}[] or C{other}[]).
@keyword fraction: Index fraction (C{float} in L{EPS}..L{EPS1}) to
interpolate intermediate B{C{points}} or C{None},
C{0} or C{1} for no I{fractional} indices and
intermediate B{C{points}}.
@return: A L{Frechet6Tuple}C{(fd, fi, fj, r, n, units)}.
@raise FrechetError: Insufficient number of B{C{points}}.
@raise RecursionError: Recursion depth exceeded C{sys.getrecursionlimit()}.
'''
n2, ps2 = _points2(points, closed=False, Error=FrechetError)
f2 = _fraction(fraction)
p2 = self.points_fraction if f2 < EPS1 else self.points_ # PYCHOK expected
f1 = self.fraction
p1 = self.points_fraction if f1 < EPS1 else self.points_ # PYCHOK expected
def dF(fi, fj):
return self.distance(p1(self._ps1, fi), p2(ps2, fj))
n2, ps2 = _points2(points, closed=False, Error=FrechetError)
return _frechet_(self._n1, f1, n2, f2, dF, self.units)
def frechet_(points1, points2, distance=None, units=''):
'''Compute the I{discrete} U{Frechet distance<https://WikiPedia.org/wiki/Frechet_distance>}
between two curves given as sets of points.
@param points1: First set of points (C{LatLon}[], C{Numpy2LatLon}[],
C{Tuple2LatLon}[] or C{other}[]).
@param points2: Second set of points (C{LatLon}[], C{Numpy2LatLon}[],
C{Tuple2LatLon}[] or C{other}[]).
@keyword distance: Callable returning the distance between a B{C{points1}}
and a B{C{points2}} point (signature C{(point1, point2)}).
@keyword units: Optional, name of the distance units (C{str}).
@return: A L{Frechet6Tuple}C{(fd, fi, fj, r, n, units)}.
@raise FrechetError: Insufficient B{C{points1}} or B{C{points2}}.
@raise RecursionError: Recursion depth exceeded C{sys.getrecursionlimit()}.
@raise TypeError: If B{C{distance}} is not a callable.
@note: I{Fractions}, intermediate B{C{points1}} or B{C{points2}} and
I{fractional} indices are I{not} supported in this L{frechet_}.
'''
if not callable(distance):
raise TypeError('%s not callable: %r' % ('distance', distance))
n1, ps1 = _points2(points1, closed=False, Error=FrechetError)
n2, ps2 = _points2(points2, closed=False, Error=FrechetError)
def dF(i, j):
return distance(ps1[i], ps2[j])
return _frechet_(n1, 1, n2, 1, dF, units)
def __init__(self, points, fraction=None, name='', units=''):
'''New L{Frechet} calculator/interpolator.
@param points: First set of points (C{LatLon}[], C{Numpy2LatLon}[],
C{Tuple2LatLon}[] or C{other}[]).
@keyword fraction: Index fraction (C{float} in L{EPS}..L{EPS1}) to
interpolate intermediate B{C{points}} or C{None},
C{0} or C{1} for no I{fractional} indices and
intermediate B{C{points}}.
@keyword name: Optional calculator name (C{str}).
@keyword units: Optional, distance units (C{str}).
@raise FrechetError: Insufficient number of B{C{points1}} or
invalid B{C{fraction}}.
'''
self._n1, self._ps1 = _points2(points,
closed=False,
Error=FrechetError)
if fraction:
self.fraction = fraction
if name:
self.name = name
if units:
self.units = units