r - Reverse and change limit of axis

Question

I am trying to create a contour plot. I would like to have depth on the Y-axis and time on the X-axis. Right now this is the code that I am using:

par <- ggplot(up_PAR, aes(Time.hour.of.the.day., Depth, z = PAR))
parplot <- par + 
           stat_contour(bins=20, aes(colour=..level..))+ 
           scale_colour_gradient(limits=c(0.000842, 0.00000000195),low="black", high="black") +
           scale_y_reverse()+
           theme_bw()+
           theme(panel.grid.major = element_blank(), panel.grid.minor = element_blank())+
           xlab("Hour of the Day")+
           ylab("Depth(m)")+
           ggtitle("Downwelling PAR (photons/m2/s), January 22nd")
direct.label(parplot)

However, I would like to extend the Depth axis to span from 0-30m. My dataset goes to 175m, but I am only interested in showing the top of the water column.

I know that I can use scale_y_continuous(limit=c(0,30)) but since I've already reversed my axis, and would like to keep it that way, I am unable to also set the limits of the axis.

Answer 1

As @aosmith already pointed out, just use the lim inside the scale_y_reverse

library(ggplot2)
set.seed(15)

ggplot(data.frame(x=sort(runif(20, 0, 20)), y=cumsum(runif(20,0 ,2))), aes(x,y)) +
    geom_point() + 
    scale_y_reverse( lim=c(10,0))