QUESTION
How do you combine separate plots (ggplot2), with different y-axis and different plot heights, yet retain alignment?
DETAIL
When combining plots with grid.arrange
(method1), with different y-axis units, they do not align. One way around this is to use gtable
(method2), but I cannot adjust the relative height of the plots.
EXAMPLE
require(ggplot2)
#Make two plots, with different y axis
x = c(1, 5)
y= c(.1, .4)
data1<-data.frame(x,y)
top<-
ggplot(data1, aes(x=x, y=y))+
geom_line()
x = c(1, 5)
y= c(100000, 400000)
data2<-data.frame(x,y)
bottom<-
ggplot(data2, aes(x=x, y=y))+
geom_line()
# Method 1 - Grid Extra
require(gridExtra)
grid.arrange(top, bottom, heights=c(.6,.3))
Method 1 results in this plot, which is misaligned due to the different length y axis labels:
#Method 2 - gtable
require(gtable)
#Extract Grobs
g1<-ggplotGrob(top)
g2<-ggplotGrob(bottom)
#Bind the tables
g<-gtable:::rbind_gtable(g1, g2, "first")
#Remove a row between the plots
g <- gtable_add_rows(g, unit(-1,"cm"), pos=nrow(g1))
#draw
grid.newpage()
grid.draw(g)
Method 2 results in aligned plots, but I cannot adjust the height of each plot.
THANKS!
In your gtable g
, you can set the relative panel heights,
require(gtable)
g1<-ggplotGrob(top)
g2<-ggplotGrob(bottom)
g<-gtable:::rbind_gtable(g1, g2, "first")
panels <- g$layout$t[grep("panel", g$layout$name)]
g$heights[panels] <- unit(c(1,2), "null")
grid.newpage()
grid.draw(g)
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