作者列表中的R森林地块上标

我想创建一个森林图，我必须把引用作为上标放在森林图中

我试过几种方法

假设我的作者在参考文献中列出了这一点

   aut<- c("a, 2018", "c, 2018", "v, 2018", "f, 2018", "f, 2017", 
            "f, 2015", "y, 2014","ya, 2014","y, 2014","j, 2013", "j, 2011",
            "j, 2011","h, 2011", "g, 2011","e, 2010","r, 2008","f, 2008",
            "gh, 2007","h, 2006","h, 2005","h, 2004","h, 2003",
            "h, 2002", "g, 2002","f, 2002","f, 2001","f, 2001", "208136/016, 2001", "208136/007, 2001",
            "f, 2000","f, 2000", "g, 1999","g, 1999", "g, 1998",
            "d , 1998","g, 1998","go, 1997","g, 1995","g, 1994",
            "r, 1991","r, 1989","r, 1988","r, 1987","r, 1983",
            "g, 1982","g, 1981","g, 1975","g, 1975")
    ref<-as.character(seq(1:48))

我也尝试过表达，但也不起作用

有人能帮我吗

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谢谢大家!

所以我找到了解决办法。不是最漂亮的，但它确实起了作用，我没有心情去寻找一些优雅的东西

aut<-list(expression("author,2011"^2,.. etc)

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autI找到了解决方案！没关系，嘿，如果你能回答自己的问题，这样别人就能从你找到的解决方案中得到帮助，那就太好了！aut
    Error in parse(text(paste(expression(aut, "^", number)))) : 
  'file' must be a character string or connection
In addition: Warning message:
In xy.coords(x, y, recycle = TRUE, setLab = FALSE) :
  NAs introduced by coercion

aut<-list(expression("author,2011"^2,.. etc)