带有坐标的ggmap，带有R之间城市之间的弯曲箭头

Question

我想制作荷兰地图，城市之间有曲线。我有两个名为df_verticles的数据框，其中包含24个城市及其纬度/经度组合。第二个数据框叫做df我想用来在lat / lon从组合到lat / lon到组合之间画一条曲线。

> head(df_vertices)
        city AmountSessions   totalkWh AmountRFID scaledAmount   scaledkWh Latitude Longitude
1    Alkmaar          13608  104554.68       1326   0.07139012 0.026941910 52.63903  4.755538
2     Almere          11281  100841.42        930   0.05006999 0.025985067 52.39447  5.282043
3 Amersfoort           7719   67663.30       1198   0.06449876 0.017435647 52.15108  5.383069
4 Amstelveen          25794  236437.93       2616   0.14084204 0.060925915 52.31724  4.859266
5  Amsterdam         402365 3880744.86      18574   1.00000000 1.000000000 52.34560  4.808834


> head(df)
  CityChargeSessions   NextCity Amount    sumkWh scaledAmount  scaledkWh Latitude_from Longitude_from Latitude_to Longitude_to
1          Amsterdam    Alkmaar   1058  8133.736   0.18438480 0.15480933      52.34560       4.808834    52.63903     4.755538
2          Amsterdam     Almere    998  7254.133   0.17392820 0.13806786      52.34560       4.808834    52.39447     5.282043
3          Amsterdam Amersfoort    566  4977.404   0.09864064 0.09473489      52.34560       4.808834    52.15108     5.383069
4          Amsterdam Amstelveen   3724 24210.289   0.64900662 0.46079423      52.34560       4.808834    52.31724     4.859266
5             Almere  Amsterdam   1034  8685.526   0.18020216 0.16531155      52.39447       5.282043    52.34560     4.808834
6         Amersfoort  Amsterdam    579  4936.823   0.10090624 0.09396251      52.15108       5.383069    52.34560     4.808834

map <- get_map(location = "Schiphol", zoom = 9, source = "google")
p1 <- ggmap(map)+
   geom_point(aes(x = Longitude, y = Latitude, size=scaledkWh), data = df_vertices, alpha =0.5)+
   scale_size_continuous(range=c(1,30)) + 
   geom_segment(data=df, aes(x=Longitude_from, y=Latitude_from, xend=Longitude_to, yend=Latitude_to),
           arrow=arrow(ends="first"), size= df$scaledAmount,alpha=0.75)

这是我到目前为止的输出：

正如您在上图中所看到的，有些线条重叠，这并不好看。任何人都可以帮我解释如何将它编码为城市之间的曲线。

非常感谢！