这是我过去解决该问题的方式(基于以下问题:获取日志空间中的边距行位置):

This is how I have solved that problem in the past (based on these questions: Get margin line locations (mgp) in user coordinates, Get margin line locations in log space):

line2user <- function(line, side) {
  lh <- par('cin')[2] * par('cex') * par('lheight')
  x_off <- diff(grconvertX(c(0, lh), 'inches', 'npc'))
  y_off <- diff(grconvertY(c(0, lh), 'inches', 'npc'))
  switch(side,
         `1` = grconvertY(-line * y_off, 'npc', 'user'),
         `2` = grconvertX(-line * x_off, 'npc', 'user'),
         `3` = grconvertY(1 + line * y_off, 'npc', 'user'),
         `4` = grconvertX(1 + line * x_off, 'npc', 'user'),
         stop("Side must be 1, 2, 3, or 4", call.=FALSE))
}

addfiglab <- function(lab, xl = par()$mar[2], yl = par()$mar[3]) {

  text(x = line2user(xl, 2), y = line2user(yl, 3), 
       lab, xpd = NA, font = 2, cex = 1.5, adj = c(0, 1))

}

par(mfrow = c(1, 2))
plot(0)
addfiglab("A")
plot(1000)
addfiglab("B")