如何在雷达图中放置 Y 轴值

Question

我的问题使用了以下示例：http://www.cmap.polytechnique.fr/~lepennec/R/Radar/RadarAndParallelPlots.html

mtcarsscaled <- as.data.frame(lapply(mtcars, ggplot2:::rescale01))
mtcarsscaled$model <- rownames(mtcars)
mtcarsmelted <- reshape2::melt(mtcarsscaled)

coord_radar <- function (theta = "x", start = 0, direction = 1) 
{
  theta <- match.arg(theta, c("x", "y"))
  r <- if (theta == "x") 
    "y"
  else "x"
  ggproto("CordRadar", CoordPolar, theta = theta, r = r, start = start, 
          direction = sign(direction),
          is_linear = function(coord) TRUE)
}

plot <- ggplot(mtcarsmelted, aes(x = variable, y = value)) +
  geom_polygon(aes(group = model, color = model), fill = NA, size = 2, show.legend = FALSE) +
  geom_line(aes(group = model, color = model), size = 2) +
  theme_bw()+
  theme(axis.text.x = element_text(colour="black",size=10), axis.text.y=element_text(size=14))+
  xlab("") + ylab("") +
  guides(color = guide_legend(ncol=2)) +
  coord_radar()

print(plot)

如何将 y 轴的值移动到雷达图上，以便它们与主要的 y 轴网格线对齐并消除图周围的黑框？

Answer 1

您可以将 y 轴值添加为带注释的文本，并通过更改 theme(...) 中的 panel.border 参数来移除黑框。

ggplot(mtcarsmelted, aes(x = variable, y = value)) +
  geom_polygon(aes(group = model, color = model), 
               fill = NA, size = 2, show.legend = FALSE) +
  geom_line(aes(group = model, color = model), size = 2) +
  xlab("") + ylab("") +
  guides(color = guide_legend(ncol = 2)) +
  coord_radar() +
  theme_bw()+

  # annotate
  annotate("text", x = 0, 
           y = seq(0, 1, 0.25), 
           label = seq(0, 1, 0.25)) +

  # remove original y-axis text / ticks & black border
  theme(axis.text.x = element_text(colour="black", size=10), 
        axis.text.y = element_blank(),
        axis.ticks.y = element_blank(),
        panel.border = element_blank()) 

旁注：同一张图表中的模型太多，难以阅读。如果你这样做是为了练习，那很好。但如果您打算使用它与他人交流，您可能希望对情节进行分面，以便在每个情节中仅显示几个模型，或者选择仅强调少数感兴趣的模型的不同配色方案。