jxn
result=data.frame(like=0,tree='')
as.character(result$tree)
as.numeric(result$like)
> result=data.frame(like=0,tree='')
> as.character(result$tree)
[1] ""
> as.numeric(result$like)
[1] 0
> is.numeric(result$like)
[1] TRUE
> is.character(result$tree)
[1] FALSE
> is.factor(result$tree)
[1] TRUE
为什么result$tree不能强制为字符型呢?
谢谢!