小弟使用R在中国地图上画点
代码如下：

library(ggplot2)
library(maptools)
x <- readShapePoly('bou2_4p.shp')
china.map <- fortify(x)


lon <- c(110.02,105.52,118.7,124.52,129.10,121.25)
lan <- c(30.48,34.09,41.43,42.21,46.32,49.34)

ggplot(china.map,aes(x=long,y=lat))+
  geom_polygon(aes(,group=group),fill='white',colour='black')+
  geom_point(aes(x=lon,y=lan),colour = 'black',size=2)

Error in data.frame(x = c(110.02, 105.52, 118.7, 124.52, 129.1, 121.25 :
  arguments imply differing number of rows: 6, 91040

请大侠指点一下什么地方错误，江湖救急