双y轴 - 右y轴的标签和背景网格线

Question

我需要在ggplot2中制作双y轴。我试图按照这里发布的@kohske解决方案：http://rpubs.com/kohske/dual_axis_in_ggplot2然而，有两件事仍然不受欢迎，我无法弄清楚如何解决它们。 1.在下面的图中，右侧y轴的标签不存在，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。这是情节：

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

他们在前面添加了一个辅助轴选项给ggplot。尝试将geoms放在一个地块上并添加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。这可以使用像sec.axis = sec_axis(~. * max(myData$y) / max(myData$y2))这样的内联方式完成，或者您可以提前计算并将其应用于第二轴和您想要在第二轴上读取的数据，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，并在计算轴时除以它。

输出：