带有 ROC 曲线的 ggplot 中的 scale_x_reverse 问题

发布于03月27日

我try 使用以下代码绘制ROC曲线:

library(titanic)
library(pROC)
library(ggplot2)
r <- roc(Survived ~ Fare, data = titanic_train)

#AUC text
auc <- auc(r)
ci <- ci.auc(r)
ci_l <- round(ci[1], 2)
ci_u <- round(ci[3], 2)

legend_text <- paste0("AUC = ", round(auc, 2), " (95% CI = ", ci_l, " - ", ci_u, ")")

#Plot
p <- ggroc(r) +
  scale_x_reverse() +
     labs(
          title="ROC",
          y = "Sensitivity",
          x = "1 - Specificity"
     ) +
     geom_segment(aes(x=1, xend=0, y=0, yend=1), color="grey", linetype="dashed") +
     annotate("text", x = 0.3, y = 0.05, label = legend_text)

print(p)

但是，当我收到这样的错误消息时，"Scale_x_Reverse"出现了问题:"已经存在x的比例. 为x添加另一个刻度，它将取代现有的刻度.

我希望X轴从0到1(因此将当前的1恢复到0).

对如何解决这个问题有什么 idea 吗？我不知道为什么它不起作用.

推荐答案

一种可能的解决方案是在ggroc()中指定legacy.axes = TRUE，然后更改geom_segment()以适应，例如

library(titanic)
library(pROC)
#> Type 'citation("pROC")' for a citation.
#> 
#> Attaching package: 'pROC'
#> The following objects are masked from 'package:stats':
#> 
#>     cov, smooth, var
library(ggplot2)

r <- roc(Survived ~ Fare, data = titanic_train)
#> Setting levels: control = 0, case = 1
#> Setting direction: controls < cases

auc <- auc(r)
ci <- ci.auc(r)
ci_l <- round(ci[1], 2)
ci_u <- round(ci[3], 2)

legend_text <- paste0("AUC = ", round(auc, 2), " (95% CI = ", ci_l, " - ", ci_u, ")")

p <- ggroc(r, legacy.axes = TRUE) +
  labs(
    title="ROC",
    y = "Sensitivity",
    x = "1 - Specificity"
  ) +
  geom_segment(aes(x=0, xend=1, y=0, yend=1), color="grey", linetype="dashed") +
  annotate("text", x = 0.3, y = 0.05, label = legend_text)

print(p)