嗨，欢迎来到 R 的世界。

mtcars  #look at this built in data set
str(mtcars) #allows you to see the classes of the variables (all numeric)

#one approach it to index with the $ sign and the as.factor function
mtcars$am <- as.factor(mtcars$am)
#another approach
mtcars[, 'cyl'] <- as.factor(mtcars[, 'cyl'])
str(mtcars)  # now look at the classes

这也适用于字符、日期、整数和其他类

由于您是 R 新手，我建议您看看这两个网站：

R 参考手册： http
://cran.r-project.org/manuals.html

R参考卡： http ://cran.r-project.org/doc/contrib/Short-
refcard.pdf