如何更改ggplot2中左右轴的范围？答案

【问题标题】：How to change the ranges of the left and the right axis in ggplot2?如何更改ggplot2中左右轴的范围？
【发布时间】：2021-12-29 00:22:02
【问题描述】：

数据

structure(list(VAR1 = 1:25, VAR2 = c(33151.4302619749, 30243.6061009354, 
29075.4630823572, 27646.1136405244, 27227.44196157, 25910.8454253342, 
26405.0119958585, 26167.0056585366, 25230.4079822407, 24976.0912545877, 
25343.7017313494, 26159.0753483146, 26957.9730021768, 27759.9504648796, 
29046.5695915796, 26946.8014342613, 28679.717757397, 28511.198514726, 
31713.1021393953, 29817.0124623543, 29296.1166847962, 30338.1835634015, 
31091.0104433836, 31006.5299473411, 31774.4212233181), VAR3 = c(0.159880385135182, 
0.271631841511188, 0.32632879125533, 0.399844578596391, 0.421938705559609, 
0.478323940647091, 0.48149816119631, 0.509588233124643, 0.551439379228908, 
0.573370058778077, 0.580567765134673, 0.580904582887182, 0.576292211835652, 
0.566802717164287, 0.588146883004088, 0.609420847255646, 0.5934221293271, 
0.622638198647242, 0.600671162470947, 0.563000351965266, 0.641578758944993, 
0.629095088526046, 0.608579189017581, 0.65220556730865, 0.63606478018115
)), class = "data.frame", row.names = c(NA, -25L))

我想用下面的代码绘制一个带有双 y 轴的图。似乎左轴的限制与红线不匹配，我想拉伸红线，最低点位于图的底部。

ggplot(df, aes(VAR1)) +
  geom_point(aes(y = VAR2), size = 3, color = '#D62728') +
  geom_line(aes(y = VAR2), size = 1, color = '#D62728', lty = 3) +
  geom_point(aes(y = VAR3*5.1e4), size = 3, color = '#1F77B4') + 
  geom_line(aes(y = VAR3*5.1e4), size = 1, color = '#1F77B4') +
  scale_y_continuous(name = 'VAR2', sec.axis = sec_axis(~./5.1e4, name = "VAR3"))

【问题讨论】：

标签： r ggplot2

【解决方案1】：

以不同方式缩放数据（并添加截距，而不仅仅是标量）。

首先，使用两个轴（故意）混淆了线条之间的真实关系。从这张图片中，人们可能会推断出这两个数字以某种方式重叠，而实际上范围相差很大（VAR2 是 25k-33k，VAR3 是 0.16-0.65）。我知道你是故意重叠这些，我添加这个注释是为了警告这种方法可能会引入视觉偏见。

zz <- c(22000, 18000)
ggplot(df, aes(VAR1)) +
  geom_point(aes(y = VAR2), size = 3, color = '#D62728') +
  geom_line(aes(y = VAR2), size = 1, color = '#D62728', lty = 3) +
  geom_point(aes(y = zz[1] + VAR3*zz[2]), size = 3, color = '#1F77B4') + 
  geom_line(aes(y = zz[1] + VAR3*zz[2]), size = 1, color = '#1F77B4') +
  scale_y_continuous(name = 'VAR2', sec.axis = sec_axis(~(. - zz[1]) / zz[2], name = "VAR3"))

【讨论】：