my bug of VG algorithm

 def visibility_graph(series):
     g = nx.Graph()

     # convert list of magnitudes into list of tuples that hold the index
     tseries = []
     n = 0
     for magnitude in series:
         tseries.append((n, magnitude))
         n += 1

     '''add nodes'''
     for i in range(len(tseries)):
         (ta, ya) = tseries[i]
         g.add_node(ta, mag=ya)

     '''add edges'''
     for a, b in combinations(tseries, 2):
         (ta, ya) = a
         (tb, yb) = b
         connect = True
         if tb - ta > 1:
             (tc, yc) = max(tseries[ta + 1:tb])  #我的算法
             print(tc,yc)
             if (yc > yb + (ya - yb) * ((tb - tc) / (tb - ta))):
                 connect = False

         # medium = tseries[ta+1 :tb]  #别人的算法
         # for tc, yc in medium:
         #     if yc > yb + (ya - yb) * ((tb - tc) / (tb - ta)):
         #         connect = False

         if connect:
             g.add_edge(ta, tb)

     return g

在第22行中,由于tseires 变成了嵌入元组, 所以max(tseries[ta + 1:tb]) 会取下标最大的值, 而非最大的第二个元素.

[(0, 0.19024852355156963),
(1, 0.6660417262541884),
(2, 0.395523497583831),
(3, 0.19024852355156963)]