如何在双y轴ggplot上显示图例 [英] how to show a legend on dual y-axis ggplot
问题描述
我试图使用ggplot组成一个双y轴图表。首先让我说,我不是在寻求讨论是否是好做法的优点。我发现它们在查看基于时间的数据以确定2个离散变量的趋势时特别有用。对此的进一步讨论更适合在我看来交叉验证。
Kohske 提供了一个很好的例子,如何做到这一点,我已经使用了很大的效果,到目前为止。然而,我在我的极限,包括一个传说为两个y轴。我也看过类似的问题这里和这里,但似乎没有解决包括图例的问题。
我有一个可重现的例子,使用ggplot的菱形数据集。
数据
库(ggplot2 )
library(gtable)
library(grid)
library(data.table)
library(scales)
grid.newpage
$ b dt.diamonds< - as.data.table(diamonds)
d1 < - dt.diamonds [,list(revenue = sum(price),
$ b $ $
$ b 图表
p1 <-ggplot (x = clear,y = revenue,fill =#4B92DB))+
geom_bar(stat =identity)+
labs
scale_fill_identity(name =,guide =legend,labels = c(Revenue))+
scale_y_continuous(labels = dollar,expand = c(0,0))+
theme(axis.text.x = element_text(angle = 90,hjust = 1),
axis.text.y = element_text(color =#4B92DB),
legend.position =bottom )
p2< - ggplot(d1,aes(x = clarity,y = stones,color =red))+
geom_point(size = 6)+
labs(x =,y =number of stones)+ expand_limits(y = 0)+
scale_y_continuous(labels = comma,expand = c(0,0))+
scale_colour_manual name ='',values = c(red,green),labels = c(Number of Stones))+
theme(axis.text.y = element_text(color =red) )+
theme(panel.background = element_rect(fill = NA),
panel.grid.major = element_blank(),
panel.grid.minor = element_blank(),
panel.border = element_rect(fill = NA,color =grey50),
legend.position =bottom)
#extract gtable
g1< - ggplot_gtable (ggplot_build(p1))
g2< - ggplot_gtable(ggplot_build(p2))
pp< ,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& $ grobs [[ia]]
ax< - ga $ children [[2]]
ax $ wides< - rev(ax $ wides)
ax $ grobs< - rev (ax $ grobs)
ax $ grobs [[1]] $ x <-ax $ grobs [[1]] $ x - 单位(1,npc)+单位(0.15,cm
g< - gtable_add_cols(g,g2 $ wides [g2 $ layout [ia,] $ l],length(g $ width) - 1)
g< - gtable_add_grob(g,ax,pp $ t,length(g $ width) - 1,pp $ b)
#draw it
grid.draw(g)
问题:有没有人知道如何获得图例的第二部分?
以下是按照p1,p2,组合p1& p2生成的图表,您会注意到p2的图例未显示在组合图表中。
p1
p2
组合p1& p2
解决方案与上面使用的技术类似,您可以提取图例,绑定它们,然后使用它们覆盖图例。
从开始
#extract legend
leg1 <-g1 $ grobs [[which(g1 $ layout $ name ==guide-box)]]
leg2< ; - g2 $ grobs [[which(g2 $ layout $ name ==guide-box)]]
g $ grobs [[which(g $ layout $ name ==guide-box )]] < -
gtable ::: cbind_gtable(leg1,leg2,first)
grid.draw(g)
>
I am trying to compose a dual y-axis chart using ggplot. Firstly let me say that I am not looking for a discussion on the merits of whether or not it is good practice to do so. I find them to be particularly useful when looking at time based data to identify trends in 2 discrete variables. A further discussion of this is better suited to crossvalidated in my opinion.
Kohske provides a very good example of how to do it, which I have used to great effect so far. I am however at my limits to include a legend for both y-axes. I have also seen similar questions here and here but none seem to address the issue of including a legend.
I've got a reproduceable example using the diamonds dataset from ggplot.
Data
library(ggplot2)
library(gtable)
library(grid)
library(data.table)
library(scales)
grid.newpage()
dt.diamonds <- as.data.table(diamonds)
d1 <- dt.diamonds[,list(revenue = sum(price),
stones = length(price)),
by=clarity]
setkey(d1, clarity)
Charts
p1 <- ggplot(d1, aes(x=clarity,y=revenue, fill="#4B92DB")) +
geom_bar(stat="identity") +
labs(x="clarity", y="revenue") +
scale_fill_identity(name="", guide="legend", labels=c("Revenue")) +
scale_y_continuous(labels=dollar, expand=c(0,0)) +
theme(axis.text.x = element_text(angle = 90, hjust = 1),
axis.text.y = element_text(colour="#4B92DB"),
legend.position="bottom")
p2 <- ggplot(d1, aes(x=clarity, y=stones, colour="red")) +
geom_point(size=6) +
labs(x="", y="number of stones") + expand_limits(y=0) +
scale_y_continuous(labels=comma, expand=c(0,0)) +
scale_colour_manual(name = '',values =c("red","green"), labels = c("Number of Stones"))+
theme(axis.text.y = element_text(colour = "red")) +
theme(panel.background = element_rect(fill = NA),
panel.grid.major = element_blank(),
panel.grid.minor = element_blank(),
panel.border = element_rect(fill=NA,colour="grey50"),
legend.position="bottom")
# extract gtable
g1 <- ggplot_gtable(ggplot_build(p1))
g2 <- ggplot_gtable(ggplot_build(p2))
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$b)
# draw it
grid.draw(g)
QUESTION: Does anyone have some tips on how to get the 2nd part of the legend to show?
The following are the charts produced in order p1, p2, combined p1&p2, you'll notice that the legend for p2 doesn't show in the combined chart.
p1
p2
combined p1 & p2
解决方案 Similar to the technique you use above you can extract the legends, bind them and then overwrite the plot legend with them.
So starting from # draw it
in your code
# extract legend
leg1 <- g1$grobs[[which(g1$layout$name == "guide-box")]]
leg2 <- g2$grobs[[which(g2$layout$name == "guide-box")]]
g$grobs[[which(g$layout$name == "guide-box")]] <-
gtable:::cbind_gtable(leg1, leg2, "first")
grid.draw(g)
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