使用 facet_wrap 时在 ggplot2 中使用具有不同比例因子的辅助 y 轴答案

【问题标题】：Using secondary y-axis in ggplot2 with different scale factor when using facet_wrap使用 facet_wrap 时在 ggplot2 中使用具有不同比例因子的辅助 y 轴
【发布时间】：2020-08-17 06:57:38
【问题描述】：

假设我有以下数据：

library(ggplot2)
library(ggthemes)

data = structure(list(origin = c("ARG", "ARG", "ARG", "ARG", "CHL", 
"CHL", "CHL", "CHL", "COL", "COL", "COL", "COL", "MEX", "MEX", 
"MEX", "MEX"), date = c(2012, 2013, 2014, 2015, 2012, 2013, 2014, 
2015, 2012, 2013, 2014, 2015, 2012, 2013, 2014, 2015), reer = c(99.200680735245, 
88.1100217095859, 91.138945064955, 38.2318792759958, 97.1355065168361, 
96.1872670893033, 93.6345905776444, 92.1029850680499, 101.123844098755, 
94.173001658586, 77.1226216761908, 59.6337376438912, 98.0983258996167, 
97.6713495865999, 92.2842729861424, 86.2605669691898), x_r = c(0.0874733578362671, 
0.0815610804254794, 0.0783917054809495, 0.0579932868099816, 0.178204232427659, 
0.16321408066481, 0.170084977520404, 0.151329817378872, 0.0498810245214703, 
0.0429419825495197, 0.0383271589817956, 0.0413797639710004, 0.246549060641858, 
0.242694346464116, 0.236773340112642, 0.269553103263527)), class = c("grouped_df", 
"tbl_df", "tbl", "data.frame"), row.names = c(NA, -16L), groups = structure(list(
    origin = c("ARG", "CHL", "COL", "MEX"), .rows = list(1:4, 
        5:8, 9:12, 13:16)), row.names = c(NA, -4L), class = c("tbl_df", 
"tbl", "data.frame")))

我正在尝试使用facet_wrap 以及使用scale_y_continuous 的sec.axis 选项的辅助y 轴绘制一个绘图。到目前为止，我得到的是以下内容：

scale = 500

ggplot(data, aes(x = date)) +
  geom_line(aes(y = x_r), size = 2, color = "red") + 
  geom_line(aes(y = reer/scale), size = 2, color = "blue") +
  facet_wrap(.~origin, ncol = 4, scales = "free_y") + 
  scale_y_continuous(
    name = "X/GDP",
    sec.axis = sec_axis(~.*scale, name = "REER")
  ) +   
  theme_bw() +
  theme(
    axis.title.y = element_text(color = "red", size = 13),
    axis.title.y.right = element_text(color = "blue", size = 13)
  ) +
  ggtitle("Export Ratio and Real Effective Exchange Rate")

但是，对于所有国家/地区，我使用的 scale 因子是恒定的（比例 = 500），我希望每个国家/地区都有不同的比例因子。像scaleFactor1 = max(x_r)/max(reerr) 这样的东西。我知道scale_y_continuousmakes 的sec.axis 选项是主y 轴的线性组合，但我希望每个国家/地区都不同。我尝试了以下方法，但它不起作用：

data = data %>% 
  group_by(origin) %>% 
  mutate(scaleFactor = max(x_r)/max(reerr)) %>% 
  mutate(reer_2 = reerr/scaleFactor)

ggplot(data, aes(x = date)) +
  geom_line(aes(y = x_r), size = 2, color = "red") + 
  geom_line(aes(y = reer), size = 2, color = "blue") +
  facet_wrap(.~origin, ncol = 4, scales = "free_y") + 
  scale_y_continuous(
    name = "X/GDP",
    sec.axis = sec_axis(~.*scaleFactor, name = "REER")
  ) +   
  theme_bw() +
  theme(
    axis.title.y = element_text(color = "red", size = 13),
    axis.title.y.right = element_text(color = "blue", size = 13)
  ) +
  ggtitle("Export Ratio and Real Effective Exchange Rate")

【问题讨论】：

标签： r ggplot2 plot axis facet-wrap

【解决方案1】：

一种方法是拆分国家/地区的数据并创建单独的图，将它们保存到列表中。然后使用 cowplot 包将它们绘制成网格布局，类似于 ggplot 中的facet_wrap。

这是您创建绘图的代码，减去 facet_wrap，创建 scaleFactor 和标题的 Country 对象。

myPlot <- function(data){

  scaleFactor <- max(data$reer) / max(data$x_r)
  Country <- data$origin

  p <- ggplot(data, aes(x = date)) +
    geom_line(aes(y = x_r), size = 2, color = "red") + 
    geom_line(aes(y = reer/scaleFactor), size = 2, color = "blue") +
    #facet_wrap(.~origin, ncol = 4, scales = "free_y") + 
    scale_y_continuous(
      name = "X/GDP",
      sec.axis = sec_axis(~.*scaleFactor, name = "REER")
    ) +   
    theme_bw() +
    theme(
      axis.title.y = element_text(color = "red", size = 13),
      axis.title.y.right = element_text(color = "blue", size = 13)
    ) +
    ggtitle(Country)
  p
}

现在split 原始数据并使用lapply 调用myPlot 函数。

data2 <- split(data, data$origin)
p_lst <- lapply(data2, myPlot)

制作标题图并使用plot_grid 将它们排列在网格中。

p0 <- ggplot() + labs(title="Export Ratio and Real Effective Exchange Rate")

library(cowplot)

p1 <- plot_grid(plotlist=p_lst, ncol=2)
pp <- plot_grid(p0, p1, ncol=1, rel_heights=c(0.1, 1))

【讨论】：