r - How to align multiple ggplot2 plots and add shadows over all of them

Question

Please download the data here!

Target: Plot an image like this:

Features: 1. two different time series; 2. the lower panel has a reverse y-axis; 3. shadows over two plots.

Possible solutions:
1. Facetting is not appropriate - (1) can not just make one facet's y axis reverse while keep the other(s) unchanges. (2) difficult to adjust the individual facets one by one.
2. Using viewports to arrange individual plots using the following codes:

library(ggplot2)
library(grid)
library(gridExtra)

##Import data
df<- read.csv("D:\R\SF_Question.csv")

##Draw individual plots
#the lower panel
p1<- ggplot(df, aes(TIME1, VARIABLE1)) + geom_line() + scale_y_reverse() + labs(x="AGE") + scale_x_continuous(breaks = seq(1000,2000,200), limits = c(1000,2000))
#the upper panel
p2<- ggplot(df, aes(TIME2, V2)) + geom_line() + labs(x=NULL) + scale_x_continuous(breaks = seq(1000,2000,200), limits = c(1000,2000)) + theme(axis.text.x=element_blank())

##For the shadows
#shadow position
rects<- data.frame(x1=c(1100,1800),x2=c(1300,1850),y1=c(0,0),y2=c(100,100))
#make shadows clean (hide axis, ticks, labels, background and grids)
xquiet <- scale_x_continuous("", breaks = NULL)
yquiet <- scale_y_continuous("", breaks = NULL)
bgquiet<- theme(panel.background = element_rect(fill = "transparent", colour = NA))
plotquiet<- theme(plot.background = element_rect(fill = "transparent", colour = NA))
quiet <- list(xquiet, yquiet, bgquiet, plotquiet)
prects<- ggplot(rects,aes(xmin=x1,xmax=x2,ymin=y1,ymax=y2))+ geom_rect(alpha=0.1,fill="blue") + coord_cartesian(xlim = c(1000, 2000)) + quiet

##Arrange plots
pushViewport(viewport(layout = grid.layout(2, 1)))
vplayout <- function(x, y) 
  viewport(layout.pos.row = x, layout.pos.col = y)
#arrange time series
print(p2, vp = vplayout(1, 1))
print(p1, vp = vplayout(2, 1))
#arrange shadows
print(prects, vp=vplayout(1:2,1))

Problems:

1. the x-axis doesn't align correctly;
2. the shadow locations are wrong (because of the incorrect line-up of x-axis).

After Googling all around:

1. I firstly noticed that "align.plots() from ggExtra" could do this job. However, it has been deprecated by the author;
2. Then I've tried the gglayout solution, but no luck - I even could not install the "cutting-edge" package;

3. Finally, I've tried the gtable solution using the following code:

   gp1<- ggplot_gtable(ggplot_build(p1))
   gp2<- ggplot_gtable(ggplot_build(p2))
   gprects<- ggplot_gtable(ggplot_build(prects))
   maxWidth = unit.pmax(gp1$widths[2:3], gp2$widths[2:3], gprects$widths[2:3])
   gp1$widths[2:3] <- maxWidth
   gp2$widths[2:3] <- maxWidth
   gprects$widths[2:3] <- maxWidth
   grid.arrange(gp2, gp1, gprects)
   

Now, the x-axis of upper and lower panel do align correctly. But the shadow positions are still wrong. And more importantly, I can not overlap the shadow plot on the two time-series. After several day's attempts, I nearly give up...

Could somebody here give me a hand?

Answer 1

You can achieve this particular plot also using just base plotting functions.

#Set alignment for tow plots. Extra zeros are needed to get space for axis at bottom.
layout(matrix(c(0,1,2,0),ncol=1),heights=c(1,3,3,1))

#Set spaces around plot (0 for bottom and top)
par(mar=c(0,5,0,5))

#1. plot
plot(df$V2~df$TIME2,type="l",xlim=c(1000,2000),axes=F,ylab="")

#Two rectangles - y coordinates are larger to ensure that all space is taken  
rect(1100,-15000,1300,15000,col="red",border="red")
rect(1800,-15000,1850,15000,col="red",border="red")

#plot again the same line (to show line over rectangle)
par(new=TRUE)
plot(df$V2~df$TIME2,type="l",xlim=c(1000,2000),axes=F,ylab="")

#set axis
axis(1,at=seq(800,2200,200),labels=NA)
axis(4,at=seq(-15000,10000,5000),las=2)


#The same for plot 2. rev() in ylim= ensures reverse axis.
plot(df$VARIABLE1~df$TIME1,type="l",ylim=rev(range(df$VARIABLE1)+c(-0.1,0.1)),xlim=c(1000,2000),axes=F,ylab="")
rect(1100,-15000,1300,15000,col="red",border="red")
rect(1800,-15000,1850,15000,col="red",border="red")
par(new=TRUE)
plot(df$VARIABLE1~df$TIME1,type="l",ylim=rev(range(df$VARIABLE1)+c(-0.1,0.1)),xlim=c(1000,2000),axes=F,ylab="")
axis(1,at=seq(800,2200,200))
axis(2,at=seq(-6.4,-8.4,-0.4),las=2)

UPDATE - Solution with ggplot2

First, make two new data frames that contain information for rectangles.

rect1<- data.frame (xmin=1100, xmax=1300, ymin=-Inf, ymax=Inf)
rect2 <- data.frame (xmin=1800, xmax=1850, ymin=-Inf, ymax=Inf)

Modified your original plot code - moved data and aes to inside geom_line(), then added two geom_rect() calls. Most essential part is plot.margin= in theme(). For each plot I set one of margins to -1 line (upper for p1 and bottom for p2) - that will ensure that plot will join. All other margins should be the same. For p2 also removed axis ticks. Then put both plots together.

library(ggplot2)
library(grid)
library(gridExtra)
p1<- ggplot() + geom_line(data=df, aes(TIME1, VARIABLE1)) + 
  scale_y_reverse() + 
  labs(x="AGE") + 
  scale_x_continuous(breaks = seq(1000,2000,200), limits = c(1000,2000)) + 
   geom_rect(data=rect1,aes(xmin=xmin,xmax=xmax,ymin=ymin,ymax=ymax),alpha=0.1,fill="blue")+
   geom_rect(data=rect2,aes(xmin=xmin,xmax=xmax,ymin=ymin,ymax=ymax),alpha=0.1,fill="blue")+
   theme(plot.margin = unit(c(-1,0.5,0.5,0.5), "lines"))

p2<- ggplot() + geom_line(data=df, aes(TIME2, V2)) + labs(x=NULL) + 
  scale_x_continuous(breaks = seq(1000,2000,200), limits = c(1000,2000)) + 
  scale_y_continuous(limits=c(-14000,10000))+
  geom_rect(data=rect1,aes(xmin=xmin,xmax=xmax,ymin=ymin,ymax=ymax),alpha=0.1,fill="blue")+
  geom_rect(data=rect2,aes(xmin=xmin,xmax=xmax,ymin=ymin,ymax=ymax),alpha=0.1,fill="blue")+
  theme(axis.text.x=element_blank(),
        axis.title.x=element_blank(),
        plot.title=element_blank(),
        axis.ticks.x=element_blank(),
        plot.margin = unit(c(0.5,0.5,-1,0.5), "lines"))


gp1<- ggplot_gtable(ggplot_build(p1))
gp2<- ggplot_gtable(ggplot_build(p2))
maxWidth = unit.pmax(gp1$widths[2:3], gp2$widths[2:3])
gp1$widths[2:3] <- maxWidth
gp2$widths[2:3] <- maxWidth
grid.arrange(gp2, gp1)