Combined plot differing X axis values

Question

This may be a repeat but I have not been able to find a solution. So I wish to plot a line plot of a genome region and underneath have a plot of the gene track below.

The problem I encounter is that the x-axis is linked in both plots so I end up losing the line graph and the gene track as in the following picture:

The code I am using to do so (Example Data) is as follows:

library(ggplot2)
library(ggbio)
library(TxDb.Hsapiens.UCSC.hg19.knownGene)
library(Homo.sapiens)

BOD<-matrix(c(1,8.3,"Group1",2,10.3,"Group1",3,19,"Group1",1,16,"Group2",2,17.6,"Group2",3,19.8,"Group2"),nrow=6,ncol=3,byrow=TRUE)
BOD<-data.frame(BOD)
names(BOD)<-c("Time","Demand","Category")
p1<-ggplot(BOD, aes(x=factor(Time), y=Demand, colour=Category, group=Category)) + geom_line()
p.txdb <- autoplot(Homo.sapiens, which = GRanges("chr1",IRanges(183800615, 183960615)))
tracks('Methylation'=p1,'Gene Track'=p.txdb)

How would I go about plotting both images with their own seperate x-axis? so I can see both plots.

Answer 1

We can use cowplot package:

# instead of autoplot use ggplot geom_alignment
p.txdb <- ggplot() + 
  geom_alignment(Homo.sapiens,
                 which = GRanges("chr1", IRanges(183800615, 183960615)))

# cowplot* to merge
cowplot::plot_grid(p1, p.txdb, nrow = 2,
                   labels = c("LinePlotLabel", "GeneTrackLabel"))

Note: Do not load cowplot using library(), it will change the default themes. Also, notice I am using geom_alignment() instead of autoplot().