双 y 轴 - 右 y 轴的标签和背景网格线

Question

我需要在ggplot2 中创建一个双 y 轴。我曾尝试遵循此处发布的@kohske 解决方案：http://rpubs.com/kohske/dual_axis_in_ggplot2 但是，仍有两件事是不受欢迎的，我不知道如何解决它们。 1. 在右 y 轴标签下方的情节中，不存在，而我想让它出现 2.右侧y轴的网格线显示在条形图的顶部，而它应该在背景中。 剧情如下：

和代码：

library(ggplot2)
library(grid)
library(gtable)

grid.newpage()
p1 <- ggplot(ex, 
         aes(factor(subgroups, levels = c('Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 
                                          'Saturday', 'Sunday')),
             y_left)) + 
  geom_bar(fill = rgb(16/255, 72/255, 128/255), stat = 'identity') + 
  theme_bw() +
  labs(x = 'weekday')
p2 <- ggplot(ex, aes(factor(subgroups,
                              levels = c('Monday', 'Tuesday', 'Wednesday', 
                                         'Thursday', 'Friday', 'Saturday', 'Sunday')), y_right)) + 
  geom_line(colour = rgb(237/255, 165/255, 6/255), group = 1) + 
  geom_point(color = rgb(237/255, 165/255, 6/255), size = 3) +
  scale_y_continuous(limits = c(0, 180)) +
  labs(y = 'name for y_left axis') +
  theme_bw() %+replace% 
  theme(panel.background = element_rect(fill = NA))
# extract gtable
g1 <- ggplot_gtable(ggplot_build(p1))
g2 <- ggplot_gtable(ggplot_build(p2))

# overlap the panel of 2nd plot on that of 1st plot
pp <- c(subset(g1$layout, name == "panel", se = t:r))
g <- gtable_add_grob(g1, g2$grobs[[which(g2$layout$name == "panel")]], pp$t, 
                 pp$l, pp$b, pp$l)

# axis tweaks
ia <- which(g2$layout$name == "axis-l")
ga <- g2$grobs[[ia]]
ax <- ga$children[[2]]
ax$widths <- rev(ax$widths)
ax$grobs <- rev(ax$grobs)
ax$grobs[[1]]$x <- ax$grobs[[1]]$x - unit(1, "npc") + unit(0.15, "cm")
g <- gtable_add_cols(g, g2$widths[g2$layout[ia, ]$l], length(g$widths) - 1)
g <- gtable_add_grob(g, ax, pp$t, length(g$widths) - 1, pp$b)

# draw it
grid.draw(g)

Answer 1

他们不久前为 ggplot 添加了辅助轴选项。尝试将geoms 放在一个图上并添加scale_y_continuous(sec.axis = sec_axis(~.-280), name = "My Second Axis")。

您可以计算比率，而不是简单的减法。这可以内联完成，使用类似sec.axis = sec_axis(~. * max(myData$y) / max(myData$y2)) 的东西，或者您可以提前计算它并将其应用于第二个轴和您打算在第二个轴上读取的数据，如下所示：

library(ggplot2)
# Create Sample Data
myData <- data.frame(x = seq(1, 10, length.out = 10), 
                     y = seq(0, 20, length.out = 10), 
                     y2 = seq(0, 100, length.out = 10))
myData.ratio <- max(myData$y) / max(myData$y2)
ggplot(myData, (aes(x=x, y=y))) +
    geom_bar(stat="identity", aes(y=y2 * myData.ratio), fill = "lightblue") +
    geom_line(color="red") +
    geom_point(color="red") +
    scale_y_continuous(sec.axis = sec_axis(~. / myData.ratio, name = "My Second Axis"))

请注意，我们将实际值乘以geom 中的比率，然后在计算轴时除以它。

输出：