def _calc(self):
"""
Calculate centroid and group distance index
"""
self.centroid = LatLng()
self.gdi = 0
self.radius = 0
n = len(self.pts)
if n > 0:
self.radius = 0
if self.fixedCentroid:
self.centroid = self.fixedCentroid
else:
lat = 0
lng = 0
for pt in self.pts:
lat += pt.lat
lng += pt.lng
self.centroid = LatLng(lat / n, lng / n)
for pt in self.pts:
dist = self.centroid.distance(pt)
self.gdi += dist
if dist > self.radius:
self.radius = dist
self.gdi /= n
self.dirty = False
class LatLngGroup:
"""
Hold a group of LatLng points
"""
def __init__(self, pts=[]):
"""
>>> str(LatLngGroup([(22.35,114.17),(22.37,114.15)]))
'(22.350000,114.170000).(22.370000,114.150000)'
"""
self.data = None
self.pts = []
for p in pts:
if isinstance(p, LatLng):
self.pts.append(p)
elif isinstance(p, tuple):
self.pts.append((LatLng(*p)))
else:
raise ValueError
self.dirty = True
# The fixed center point
self.fixedCentroid = None
def get_centroid(self):
"""
@return A LatLng object of centroid
>>> str(LatLngGroup([LatLng(0,0) , LatLng(10,0),LatLng(0,10),LatLng(10,10)]).get_centroid())
'(5.000000,5.000000)'
>>> str(LatLngGroup([LatLng(22.252195,113.866299)]).get_centroid())
'(22.252195,113.866299)'
"""
if self.dirty:
self._calc()
return self.centroid
def get_gdi(self):
"""
Get Group Distance Index (average)
"""
if self.dirty:
self._calc()
return self.gdi
def get_radius(self):
if self.dirty:
self._calc()
return self.radius
def append(self, pt):
"""
@type pt gogogo.geo.LatLng
"""
self.pts.append(pt)
self.dirty = True
def remove(self, pt):
self.pts.remove(pt)
self.dirty = True
def toString(self, precision):
pts_str = []
for p in self.pts:
pts_str.append(p.toString(precision))
return ",".join(pts_str)
def dup(self):
"""
Duplicate a copy of this group exclude the contained
points.
"""
object = copy.copy(self)
object.pts = self.pts[:]
object.dirty = True
return object
def __str__(self):
pts_str = []
for p in self.pts:
pts_str.append(str(p))
return ".".join(pts_str)
def __len__(self):
return len(self.pts)
def _calc(self):
"""
Calculate centroid and group distance index
"""
self.centroid = LatLng()
self.gdi = 0
self.radius = 0
n = len(self.pts)
if n > 0:
self.radius = 0
if self.fixedCentroid:
self.centroid = self.fixedCentroid
else:
lat = 0
lng = 0
for pt in self.pts:
lat += pt.lat
lng += pt.lng
self.centroid = LatLng(lat / n, lng / n)
for pt in self.pts:
dist = self.centroid.distance(pt)
self.gdi += dist
if dist > self.radius:
self.radius = dist
self.gdi /= n
self.dirty = False
def set_fixed_centroid(self, center):
"""
Set a fixed centroid. A group with fixed centroid always use the assigned
point as the centroid independent of the points contained.
>>> l = LatLngGroup([LatLng(0,0) , LatLng(10,0),LatLng(0,10),LatLng(10,10)])
>>> l.set_fixed_centroid(LatLng(7,7))
>>> str(l.get_centroid())
'(7.000000,7.000000)'
"""
self.fixedCentroid = center
self.dirty = True
def get_fixed_centroid(self):
return self.fixedCentroid
def set_data(self, data):
"""
Set user customized data
"""
self.data = data
def get_data(self):
"""
Get user customized data
"""
return self.data