R语言：使用plot（）输出图片出现Error in as.double(y) : cannot coerce type 'S4' to vector of type 'double'

代码如下

library(REmap)
set.seed(125)
origin = rep("武汉",10)
destination = c('上海','广州','大连','南宁','南昌',
                '拉萨','长春','包头','重庆','常州')
dat = data.frame(origin,destination)
out = remap(dat,title = "by梧桐",subtitle = "")
plot(out)