修改ggplot2分面右栏默认的顺序

structure(c(2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L,
2L, 2L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L,
1L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L), .Label = c("after",
"before"), class = "factor")
以上是用edit调用的编辑器中的描述，R默认after在前，before在后，怎么样修改才能before在前，after在后

这个问题
可以 .Label =c( "before"，"after") 调整顺序的说