Various facet_grid y-axis labels and sizes

Question

I am stuck with the following problem:

I want to display different characteristics of timeseries in one plot (with several subtitles). To align the areas of the diagram and for easy creation, I use ggplot2its function facet_grid.

However, I want to change only one axis label (for example, the upper graph to a percentage).

In addition, I want to change the height sizes of each plot, so that the upper graph is approximately two times larger than the lower.

Many thanks for your help!

Example

require(ggplot2)

#simulate some data
df <- data.frame(date=c(1:1000),
              value=cumsum(rnorm(1000)),
              volume=abs(rnorm(1000)*10))

#melt for ggplot
df_melt <- melt(df, id=c("date"),measure.vars=c("value","volume"))

#plot
ggplot(df_melt, aes(x=date, y=value)) + geom_line() + 
       facet_grid(variable~., scales = "free")

which leads to something like this:

Answer 1

You can change grobsyour schedule to do this.

library(ggplot2)
library(grid)
library(scales)

#plot
p <- ggplot(df_melt, aes(x=date, y=value)) + 
            geom_line() + 
            facet_grid(variable~., scales = "free")

# change facet heights
g1 <- ggplotGrob(p) 
g1$heights[[3]] <- unit(2, "null") 

# change labels - create second plot with percentage labels (nonsese % here)
p2 <- ggplot(df_melt, aes(x=date, y=value)) + 
              geom_line() + 
              facet_grid(variable~., scales = "free") +
              scale_y_continuous(labels = percent_format())

g2 <- ggplotGrob(p2) 

#Tweak axis - overwrite one facet
g1[["grobs"]][[2]] <- g2[["grobs"]][[2]]

grid.newpage()
grid.draw(g1)