def constrained_cells_center(self):
""" calculate cell centers giving preference to constrained
nodes
"""
for c in np.arange(self.Ncells()):
nodes=self.cell_to_nodes(c)
constrained=(self.nodes['constrained'][nodes]==C_FIXED)
points=self.nodes['x'][nodes]
# for starters, only invoke the special logic when there
# at least three constrained nodes
ncon=np.sum(constrained)
if ncon==0: # regular
self.cells['_center'][c] = utils.poly_circumcenter(points)
elif ncon==1:
ci=np.nonzero(constrained)[0][0]
nn=len(constrained)
constrained[(ci+1)%nn]=True
constrained[(ci-1)%nn]=True
self.cells['_center'][c] = utils.poly_circumcenter(points[constrained])
else:
print ".",
self.cells['_center'][c] = utils.poly_circumcenter(points[constrained])
print
return self.cells['_center']
