gtable snippet for composite ggplot2 plots

library(ggplot2)
library(gtable)
 
# create example data
set.seed(42)
dataset_names <- c("Human", "Mouse", "Fly", "Worm")
datasets <- data.frame(name = factor(dataset_names, levels=dataset_names), parity = factor(c(0, 0, 1, 0)), v50 = runif(4, max=0.5), y=1:4)
data <- data.frame( dataset1 = rep(datasets$name, 4), dataset2 = rep(datasets$name, each = 4), z = runif(16,min = 0, max = 0.5) )
 
pal <- c("#dddddd", "#aaaaaa")
 
## set up individual plots
 
# heatmap
new_theme_empty <- theme_bw()
new_theme_empty$line <- element_blank()
new_theme_empty$rect <- element_blank()
new_theme_empty$strip.text <- element_blank()
new_theme_empty$axis.text <- element_blank()
new_theme_empty$plot.title <- element_blank()
new_theme_empty$axis.title <- element_blank()
new_theme_empty$legend.position <- "none"
new_theme_empty$plot.margin <- structure(c(0, 0, 0, 0), unit = "lines", valid.unit = 3L, class = "unit")
new_theme_empty$axis.ticks <- element_blank()
new_theme_empty$axis.title.x <- element_blank()
new_theme_empty$axis.title.y <- element_blank()
 
p <- ggplot( data, aes(dataset1, dataset2, fill=z) ) + geom_raster() 
p <- p + coord_fixed()
p <- p + scale_fill_gradient2(midpoint=0.5, mid="black", low="#56B1F7", high="red", name="", breaks=c(0,0.25,0.5,0.75,1), limits=c(0,0.5)) 
p <- p + scale_x_discrete(expand=c(0,0)) + scale_y_discrete(expand=c(0,0))
plegend <- p + theme(legend.direction="horizontal") 
pmiddle <- p + new_theme_empty
 
# top bar chart
theme_partly_empty <- theme_bw()
theme_partly_empty$rect <- element_blank()
theme_partly_empty$strip.text <- element_blank()
theme_partly_empty$axis.text.x <- element_blank()
theme_partly_empty$plot.title <- element_blank()
theme_partly_empty$legend.position <- "none"
theme_partly_empty$plot.margin <- structure(c(0, 0, 0, 0), unit = "lines", valid.unit = 3L, class = "unit")
theme_partly_empty$axis.ticks.x <- element_blank()
theme_partly_empty$axis.title.x <- element_blank()
theme_partly_empty$panel.grid.major.x <-element_blank()
theme_partly_empty$panel.grid.minor <-element_blank()
 
p <- ggplot( datasets, aes(name, v50, fill=parity)) + geom_bar(stat="identity")
p <- p + theme_partly_empty
p <- p + scale_fill_manual(values=pal)
p <- p + scale_y_continuous(expand=c(0,0), breaks=0.1*1:5) + scale_x_discrete(expand=c(0,0))
p <- p + ylab(expression(v[50]))
ptop <- p
 
# right bar chart
theme_partly_empty <- theme_bw()
theme_partly_empty$rect <- element_blank()
theme_partly_empty$strip.text <- element_blank()
theme_partly_empty$plot.title <- element_blank()
theme_partly_empty$legend.position <- "none"
theme_partly_empty$plot.margin <- structure(c(0, 0, 0, 0), unit = "lines", valid.unit = 3L, class = "unit")
theme_partly_empty$axis.text.y <- element_blank()
theme_partly_empty$axis.ticks.y <- element_blank()
theme_partly_empty$axis.title.y <- element_blank()
theme_partly_empty$panel.grid.major.y <-element_blank()
theme_partly_empty$panel.grid.minor <-element_blank()
 
p <- ggplot( datasets, aes(name, v50, fill=parity)) + geom_bar(stat="identity") + coord_flip()
p <- p + theme_partly_empty
p <- p + scale_fill_manual(values=pal)
p <- p + scale_y_continuous(expand=c(0,0), breaks=0.1*1:5) + scale_x_discrete(expand=c(0,0))
p <- p + ylab(expression(v[50]))
pright <- p
 
# left strip of labels
p <- ggplot( datasets, aes(xmin=0, xmax=1, ymin=y, ymax=y+1, fill=parity)) + geom_rect()
p <- p + new_theme_empty
p <- p + scale_fill_manual(values=pal)
p <- p + geom_text(aes(x=1, y=y+0.5, label=paste0(name, " ")), hjust=1, vjust=0.5)
p <- p + scale_y_discrete(expand = c(0,0)) + scale_x_continuous(expand=c(0,0))
pleft <- p
 
# bottom strip of labels
p <- ggplot( datasets, aes(xmin=y, xmax=y+1, ymin=0, ymax=1, fill=parity)) + geom_rect()
p <- p + new_theme_empty
p <- p + scale_fill_manual(values=pal)
p <- p + geom_text(aes(y=1, x=y+0.5, label=paste0(name, " ")), hjust=1, vjust=0.5, angle=90)
p <- p + scale_x_discrete(expand = c(0,0)) + scale_y_continuous(expand = c(0,0))
pbottom <- p
 
## create the layout, centered around the heatmap
g <- gtable_filter(ggplotGrob(pmiddle), pattern = "panel", trim = TRUE, fixed=TRUE)
g <- gtable_add_rows(g, unit(0.2, "null"), 0) # left labels
g <- gtable_add_rows(g, unit(0.2, "null"), 2) # right bar chart
g <- gtable_add_rows(g, unit(0.05, "null"), 2) # space for axis label 1/2
g <- gtable_add_rows(g, unit(0.05, "null"), 2) # space for axis label 2/2
g <- gtable_add_cols(g, unit(0.05, "null"), 0) # space for axis label 1/2
g <- gtable_add_cols(g, unit(0.05, "null"), 0) # space for axis label 2/2
g <- gtable_add_cols(g, unit(0.2, "null"), 0) # top bar chart
g <- gtable_add_cols(g, unit(0.2, "null"), 4) # bottom labels
 
# gtable_show_layout(g)
 
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(ptop), pattern = "ylab", trim = TRUE, fixed=TRUE), 1, 2)
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(ptop), pattern = "axis-l", trim = TRUE, fixed=TRUE), 1, 3)
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(ptop), pattern = "panel", trim = TRUE, fixed=TRUE), 1, 4)
 
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(pleft), pattern = "panel", trim = TRUE, fixed=TRUE), 2, 1, 2, 3)
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(pbottom), pattern = "panel", trim = TRUE, fixed=TRUE), 3, 4, 5)
 
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(pright), pattern = "panel", trim = TRUE, fixed=TRUE), 2, 5)
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(pright), pattern = "axis-b", trim = TRUE, fixed=TRUE), 3, 5)
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(pright), pattern = "xlab", trim = TRUE, fixed=TRUE), 4, 5)
 
g <- gtable_add_grob(g, gtable_filter(ggplotGrob(plegend), pattern = "guide-box", trim = TRUE, fixed=TRUE), 5, 1, 5, 3)
g <- gtable_add_grob(g, textGrob("\nMedian expression\ndistance of\n1:1 orthologs\n\n\n\n", gp = gpar(fontsize = 12)), 3, 1, 5, 3)
 
 
grid.newpage()
grid.draw(g)
 
png(paste0("test.png"), width = 10, height = 10, units = "in", res=300)
grid.draw(g)
dev.off()