from scipy.spatial import Delaunay, distance
from .abssimcomplex import SimplicialComplex
from . import facesiter, get_allpoints
def calculate_distmatrix(points, labels, distfcn):
return {(labels[i], labels[j]): distfcn(points[i], points[j])
for i in range(len(labels)) for j in range(len(labels))}
def contain_detachededges(simplex, distdict, epsilon):
if len(simplex) == 2:
return (distdict[simplex[0], simplex[1]] > 2*epsilon)
else:
for face in facesiter(simplex):
contained = contain_detachededges(face, distdict, epsilon)
if contained:
return True
return False
class AlphaComplex(SimplicialComplex):
def __init__(self,
points,
epsilon,
labels=None,
distfcn=distance.euclidean):
self.pts = points
self.labels = (range(len(self.pts))
if (labels is None or len(labels) != len(self.pts))
else labels)
self.epsilon = epsilon
self.distfcn = distfcn
self.import_simplices(self.construct_simplices(self.pts,
self.labels,
self.epsilon,
self.distfcn))
def construct_simplices(self, points, labels, epsilon, distfcn):
distdict = calculate_distmatrix(points, labels, distfcn)
delaunayobj = Delaunay(points)
simplices = []
for simplexnda in delaunayobj.simplices:
simplex = tuple(simplexnda)
detached = [contain_detachededges(face, distdict, epsilon) for face in facesiter(simplex)]
if True in detached and len(simplex) > 2:
simplices += [face for face, notkeep in zip(facesiter(simplex), detached)
if not notkeep]
else:
simplices.append(simplex)
simplices = map(lambda simplex: tuple(sorted(simplex)), simplices)
simplices = list(set(simplices))
allpts = get_allpoints(simplices)
simplices += [(point,) for point in (set(labels)-allpts)]
return simplices
