dear all：
           在Rstudio里面输入执行过的代码，ctrl+s 保存后，下次打开该R文件，文件中执行过的代码需要再次执行，不然会报错，
           例：
manager <- c(1,2,3,4,5)
date <- c("10/24/08","10/28/08","10/1/08","10/12/08",
          "5/1/08")
country <- c("US","US","UK","UK","UK")
gender <- c("M","F","F","M","F")
age <- c(32,45,25,39,99)
q1 <- c(5,3,3,3,2)
q2 <- c(4,5,5,3,2)
q3 <- c(5,2,5,4,1)
q4 <- c(5,5,5,NA,2)
q5 <- c(5,5,2,NA,1)
leadership <- data.frame(manager,date,country,gender,age,q1,q2,
                       q3,q4,q5,stringsAsFactors = FALSE)


当下次打开该文件，输入leadership，错误: 找不到对象'leadership'

请问这个怎么解决