在ggplot中的循环内使用direct.label来获取geom_contour

Question

**以我的数据集示例进行编辑”

我目前正在R中的一个循环上，从ggplot中的21个模型输出电子表格中生成21个轮廓图。整个循环现在可以正常工作并打印为单个pdf，但是我想在轮廓上向每个图添加direct.label。在确保循环仍然执行的同时，我不确定如何执行此操作？

我的数据：

x      y      z
0.175  1.97   1113.17
0.175  1.975  1112.31
0.175  1.98   1111.44
0.175  1.985  1110.66
0.175  1.99   1109.72
0.175  1.995  1109.28
0.175  2      1107.6
0.18   0      1321.99
0.18   0.005  1321.99
0.18   0.01   1321.99
0.18   0.015  1321.99
0.18   0.02   1321.99
0.18   0.025  1321.99
0.18   0.03   1321.99
0.18   0.035  1321.99
0.18   0.04   1321.99

我的代码：

filenames <- list.files(path=".",
                    pattern="csv", 
                    full.names=TRUE)
pdfnames <- paste(substr(filenames, 1, nchar(filenames)-4),".pdf",sep="")
pdfmaster <- paste(substr(filenames,1,15),".pdf",sep="")

# List of variables being displayed
variable = c("Dimensionless potential temperature", 
         "Melt fraction",
         "Melting rate",
         ...)

#Creates a contour plot in ggplot of the variable in xz space
makeplot <- function(filename) {
xx <- which(filenames==filename)
  data <- as.data.frame(read.csv(file=filename), header = FALSE)
  ggplot(data=data, mapping = aes(x = data[,2], 
                              y=data[,1], 
                              z = data[,3])) +

    geom_raster(data=data, aes(fill=data[,3]), show.legend=TRUE, interpolate         
 = FALSE) +
    scale_fill_gradient(limits=range(data[,3]), high = 'red', low = 'white')   +
    geom_contour(bins = 30, colour = "black") +
    xlab(label = "Distance from ridge axis") +
    ylab(label = "Depth") +
    theme_bw()+
    coord_cartesian(
      ylim = c(0,1), xlim = c(0,2))+
    scale_x_continuous(expand = c(0, 0)) + 
    scale_y_continuous(expand = c(0, 0)) +
    guides(fill=guide_legend(title=variable[xx]), 
           guide_colorbar(title=NULL)) 

}

# Making one pdf file per plot
for (f in 1:length(filenames)) {
  pdf(file=pdfnames[f], height=3, width=6)
  print(makeplot(filenames[f]))
  dev.off()
}

# Making all plots in one pdf
pdf(file=pdfmaster[1], height=6, width=12)
for (f in 1:length(filenames)) {
  print(makeplot(filenames[f]))
}
dev.off()