The perils of aligning plots in ggplot

Question

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:

enter image description here

#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. enter image description here

THANKS!

This might help

Simon O'Hanlon
– Simon O'Hanlon

2014-06-20 18:17:53 +00:00
Commented Jun 20, 2014 at 18:17 — Simon O'Hanlon
– Simon O'Hanlon, Commented Jun 20, 2014 at 18:17

baptiste · Accepted Answer · 2016-05-26 01:39:49Z

19

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)

edited May 26, 2016 at 1:39

answered Jun 20, 2014 at 18:27

baptiste

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3 Comments

wab Over a year ago

Works flawlessly, and much better results than the grid.arrange method. Thanks.

JG11235 Over a year ago

Thanks for the great answer! But perhaps something changed in updates of grid, but now (version 3.3.0) for this to work the second line must be: g$heights[panels] <- unit(c(2,1), "null")

baptiste Over a year ago

@RNoob correct, things have changed at that level in both grid and ggplot2

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