my bug of VG algorithm

 1 def visibility_graph(series):
 2     g = nx.Graph()
 3 
 4     # convert list of magnitudes into list of tuples that hold the index
 5     tseries = []
 6     n = 0
 7     for magnitude in series:
 8         tseries.append((n, magnitude))
 9         n += 1
10 
11     '''add nodes'''
12     for i in range(len(tseries)):
13         (ta, ya) = tseries[i]
14         g.add_node(ta, mag=ya)
15 
16     '''add edges'''
17     for a, b in combinations(tseries, 2):
18         (ta, ya) = a
19         (tb, yb) = b
20         connect = True
21         if tb - ta > 1:
22             (tc, yc) = max(tseries[ta + 1:tb])  #我的算法
23             print(tc,yc)
24             if (yc > yb + (ya - yb) * ((tb - tc) / (tb - ta))):
25                 connect = False
26 
27         # medium = tseries[ta+1 :tb]  #别人的算法
28         # for tc, yc in medium:
29         #     if yc > yb + (ya - yb) * ((tb - tc) / (tb - ta)):
30         #         connect = False
31 
32         if connect:
33             g.add_edge(ta, tb)
34 
35     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)]