在ggplot2中构建双y轴图的功能

Question

我正在测试一个函数来在ggplot2中构建一个双y轴图。它工作但我无法从输入图形中获取一些元素。我用两个数据框Base1和Base2构建了这两个图表（我在最后一部分添加了dput()版本）：

library(ggplot2)
library(scales)
library(gtable)
#Graph 1
g1<-ggplot(Base1, aes(x = Month, y = value, fill = variable)) +
  geom_bar(stat="identity",colour="black",size=1) +
  scale_y_continuous(labels = comma,breaks=pretty_breaks(n=7),
                     limits=c(0,max(Base1$value,na.rm=T))) +
  theme(axis.text.x=element_text(angle=90,colour="grey20",face="bold",size=12),
        axis.text.y=element_text(colour="grey20",face="bold",hjust=1,vjust=0.8,size=15),
        axis.title.x=element_text(colour="grey20",face="bold",size=16),
        axis.title.y=element_text(colour="grey20",face="bold",size=16)) +
  xlab('Month')+ylab('')+ ggtitle("My graph") +
  theme(plot.title = element_text(lineheight=3, face="bold", color="black",size=24)) +
  theme(legend.text=element_text(size=14),
        legend.title=element_text(size=14)) +
  scale_fill_manual(name = "variable", 
                    label = "Power", 
                    values = "#FF6C91")  

第二个：

#Graph2
colors=c("red","darkgreen")
g2<-ggplot(Base2, aes(x=Month, y=value, color=variable))+ 
  geom_line(aes(group=variable),size=1.3) +
  geom_point(size=3.8, shape=21, fill="white") + 
  scale_color_manual(values=colors)+ ggtitle("My graph")

使用这两个图形，我使用下一个函数，两个制作一个双y轴图：

double_axis_graph <- function(graf1,graf2){
  graf1 <- graf1

  graf2 <- graf2



  gtable1 <- ggplot_gtable(ggplot_build(graf1))

  gtable2 <- ggplot_gtable(ggplot_build(graf2))



  par <- c(subset(gtable1[['layout']], name=='panel', select=t:r))

  graf <- gtable_add_grob(gtable1, gtable2[['grobs']][[which(gtable2[['layout']][['name']]=='panel')]],

                          par['t'],par['l'],par['b'],par['r'])



  ia <- which(gtable2[['layout']][['name']]=='axis-l')

  ga <- gtable2[['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')

  graf <- gtable_add_cols(graf, gtable2[['widths']][gtable2[['layout']][ia, ][['l']]], length(graf[['widths']])-1)

  graf <- gtable_add_grob(graf, ax, par['t'], length(graf[['widths']])-1, par['b'])

  return(graf)

}

所以，当我用这个来构建两个轴图时，结果显示了双轴，但我不能将输入图形中的其他元素作为一个完整的图例;而且，当我加入图表时，只显示其中一个而另一个丢失。我将该函数应用于下一个结果：

plot(double_axis_graph(g1,g2))

在这种情况下，条形图（g1）消失，我无法使用g2中的元素完成图例。两轴工作正常。在第二次测试中我得到了这个结果：

plot(double_axis_graph(g2,g1))

在这种情况下，我从g2丢失了系列，而图例中没有来自g1的元素。我想完成该功能，以在图表中的所有系列的图例中显示图形和元素。我的数据框的dput()版本是下一个：

Base1<-structure(list(Month = c("m11", "m12", "m13", "m14", "m15", "m16"
), variable = structure(c(1L, 1L, 1L, 1L, 1L, 1L), .Label = "Power", class = "factor"), 
    value = c(28101696.45, 28606983.44, 30304944, 32583849.36, 
    34791542.82, 40051050.24)), .Names = c("Month", "variable", 
"value"), row.names = c(NA, -6L), class = "data.frame")

Base2<-structure(list(Month = c("m11", "m12", "m13", "m14", "m15", "m16", 
"m11", "m12", "m13", "m14", "m15", "m16"), variable = structure(c(1L, 
1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("Index1", 
"Index2"), class = "factor"), value = c(0.044370892419913, 0.0437161234641523, 
0.0516857394621815, 0.0495793011485982, 0.0506456741259283, 0.0314653057147897, 
0.0299405579124744, 0.0296145768664101, 0.0269727649059507, 0.0250663815369419, 
0.0233469715385275, 0.0201801611981898)), .Names = c("Month", 
"variable", "value"), row.names = c(NA, -12L), class = "data.frame")

非常感谢你的帮助！

Answer 1

寻求解决方案的第一步：

g1.1 <- g1 + theme_bw() + theme(legend.position="top")
g2.1 <- g2 + theme_bw() + theme(panel.grid=element_blank()) +
    theme(panel.background = element_rect(fill = NA))
plot(double_axis_graph(g1.1,g2.1))

现在我们需要修复：

• 到处都是奇怪的灰色背景 - 编辑：修复它！
• 传奇

为了做那些根本有缺陷的事情而活下来Hadley's wrath。

Answer 2

我使用了一些人代码来构建我自己的here

grid.newpage()

# two plots
p1 <- ggplot(fuel, aes(x=date, y=mpg)) + geom_line() + 
  theme_bw() + xlab("Date") + ylab("MPG (Black)")
p2 <- ggplot(fuel, aes(x=date, y=avg.temp)) + 
  xlab("Date") + ylab("AVG Temp (Red)") +
  geom_line(colour="red") + theme_bw() + 
  theme(axis.title.y=element_text(angle = -90)) %+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
alab <- g2$grobs[[which(g2$layout$name=="ylab")]]
ia <- which(g2$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$widths) - 1 )
g <- gtable_add_cols(g, g2$widths[g2$layout[ia, ]$l], 
                     length(g$widths) - 1 )
g <- gtable_add_grob(g, ax, pp$t, length(g$widths) - 2, pp$b)
g <- gtable_add_grob(g, alab, pp$t, length(g$widths) - 1, pp$b)

grid.draw(g)

Answer 3

sec_axis改编自here的另一种更智能的方法。

优势：

1. 原生辅助轴，只创建一个ggplot对象。
2. 没有涉及明确调整轴对象的黑客。

缺点：必须事先定义两个轴的限制。

有关详细信息，请参阅sec_axis documentation和blog post（日语）。



# You must define limits first

AXIS1_MIN = 0
AXIS1_MAX = max(Base1$value)
AXIS2_MIN = min(Base2$value)
AXIS2_MAX = max(Base2$value)

scale_to_value1 <- function(values) rescale(values, to = c(AXIS1_MIN, AXIS1_MAX))
scale_to_value2 <- function(values) rescale(values, to = c(AXIS2_MIN, AXIS2_MAX))

ggplot() +
  geom_bar(aes(x = Month, y = value, fill = variable), data = Base1, stat="identity",colour="black",size=1) +
  geom_line(aes(x = Month, y = scale_to_value1(value),color = variable, group = variable), data = Base2, size=1.3) +
  scale_y_continuous(labels = comma,breaks=pretty_breaks(n=7),
                     limits=c(AXIS1_MIN, AXIS1_MAX),
                     sec.axis = sec_axis( ~ scale_to_value2(.), name = "value2")) +
  scale_color_manual(name = "variable", 
                    label = c("Index1", "Index2"), 
                    values = c("Index1" = "red", "Index2" = "green")) +
  scale_fill_manual(name = "variable", 
                    label = "Power",
                    values = "#FF6C91") +
  theme(axis.text.x=element_text(angle=90,colour="grey20",face="bold",size=12),
        axis.text.y=element_text(colour="grey20",face="bold",hjust=1,vjust=0.8,size=15),
        axis.title.x=element_text(colour="grey20",face="bold",size=16),
        axis.title.y=element_text(colour="grey20",face="bold",size=16)) +
  xlab('Month')+ylab('')+ ggtitle("My graph") +
  theme(plot.title = element_text(lineheight=3, face="bold", color="black",size=24)) +
  theme(legend.text=element_text(size=14),
        legend.title=element_text(size=14))