平滑锯齿状的geom_segment看起来像geom_smooth

Question

我试图通过geom_segment在地块中添加参考线。

简化示例：

tryCatch({
spaghetti_smooth_ref = qplot(age,T_self, data=sest,geom="blank") + 
    geom_smooth(method='lm',alpha=0.1, colour = "black") + 
    geom_segment(aes(x = 16, xend = 45,y = coef(us_ref)["(Intercept)"], yend = coef(us_ref)["(Intercept)"] + coef(us_ref)["age"] * 45), linetype = "solid", colour = "#5e8fb0", alpha = 0.5, size = 0.1) + 
    facet_wrap(~ country)+
    scale_linetype_discrete()
}, error = function(e){warning(e)})

如下所示，geom_smooth()的呈现速度比geom_segment()更为流畅。

我该如何改进？在Mac上的Rstudio中查看并以PDF格式呈现时，情况相同。我还使用原始数据和geom_smooth()绘制了完全相同的斜率，一旦使用geom_segment()，它们仍然不同。

Answer 1

尽管这个问题已有5年历史了，但我最近遇到了同样的问题并能够解决。希望我的回答可以帮助其他经历类似的事情。

您可以创建一个附加的数据框，其中包含x轴和y轴的最小值和最大值。然后使用geom_line()添加所需的行。

data_df = data.frame(Gender = rep(c("Female", "Male"),each = 10),
                     Height = c(63.26153, 61.56266, 64.80651, 63.29383, 66.44624, 67.12988, 64.13034, 66.64640, 64.74866, 73.08489, 
                                62.01556, 72.80084, 69.28989, 67.56494, 68.01175, 70.99855, 68.19854, 71.81611, 73.08489, 70.95103),
                     Weight = c(126.4268, 131.7959, 156.0956, 159.8213, 135.6089, 146.6043, 121.2926, 156.4250, 133.5414, 158.2851,
                                117.6670, 206.8282, 179.5619, 156.1813, 175.0151, 195.9590, 176.4568, 205.9251, 230.6788, 196.6997))

model = lm(Weight~Height, data = data_df)

lines_df = data.frame(Height = c(min(data_df$Height), max(data_df$Height)),
                      Weight = c(coef(model)["(Intercept)"] + coef(model)["Height"] * min(data_df$Height),
                                 coef(model)["(Intercept)"] + coef(model)["Height"] * max(data_df$Height)))

ggplot(data_df, aes(x = Height, y = Weight)) +
  geom_smooth(method = "lm", alpha = 0.1, colour = "black", size = 0.5) +
  geom_line(aes(y = Weight), data = lines_df, linetype = "solid", colour = "#5e8fb0", size = 0.5)+
  facet_grid(.~Gender)

Answer 2

你能不能用abline定义自己的参考线？ E.g。

+ geom_abline(intercept = 48.5, slope = 0.1)