R in Action求助

polyphgia

library(leaps)
states<-as.data.fr ame(state.x77[,c("Murder","Population",
                                   "Illiteracy","Income","Frost")])
leaps<-regsubsets(Murder~Population+Illiteracy+Income+Frost,
                  data = states, nbest = 4)

subsTable<-function(obj){
  x<-summary(leaps)
  m<-cbind(round(x[[scale]],3),x$which[,-1])
  colnames(m)[1]<-scale
  m[order(m[,1]),]
}

subsTable(leaps,scale = "adjr2")

最后一步报错：
Error in subsTable(leaps, scale = “adjr2”) : 参数没有用(scale = “adjr2”)
我试了一下，function里面的

m<-cbind(round(x[[scale]],3),x$which[,-1])

这一步报错：
Error in x[[scale]] : 类别为’closure’的下标不对
看不懂求解