geom_abline在ggplot2 r软件包中与geom_dotplot不符合GEOM_DOTPLOT

Question

这个问题与ggplot2 r软件包有关。为什么使用GEOM_DOTPLOT绘制的斜率数量会截断Geom_abline的截距？尝试以下示例：

testdata <- data.frame(predictor = c(0,1), dependent = c(0,2))

testplot <- ggplot(NULL) +
             geom_dotplot(data = testdata, aes(x = factor(predictor), y = dependent), binaxis = "y", stackdir = "center") +
             geom_abline(aes(intercept = 0, slope = 2))
testplot #The line is off

testplot <- ggplot(NULL) +
             geom_dotplot(data = testdata, aes(x = factor(predictor), y = dependent), binaxis = "y", stackdir = "center") +
             geom_abline(aes(intercept = 0 - 2, slope = 2))
testplot #The line aligns with the dots as expected

这是一个错误还是我在做愚蠢的事情？谢谢。