R语言学习-问题解决-Error in output$nodeID : $ operator is invalid for atomic vectors

问题：在使用"$"符查看变量列的时候，报错Error in output$nodeID : $ operator is invalid for atomic vectors

output <- data$score
output <- cbind(nodeID=dat$nodeID,score=output)
head(output$nodeID)
 Error in output$nodeID : $ operator is invalid for atomic vectors
#查看output的类型，发现是matrix
class(output)
 [1] "matrix"
#""才能用“$”，这里改用[,]操作就行
head(output[,1])