How to put latitude on Y axis in hovmoller plot?

Question

I am plotting hovmoller plot for three rasters but the function plots the latitude on the x axis and the time on the y axis. normally (much easier to read) latitude is on the Y axis. Reproducible example:

library("rasterVis")
r <- raster(nrows=10, ncols=10)
r <- setValues(r, 1:ncell(r))
r1 <- raster(nrows=10, ncols=10)
r1 <- setValues(r1, 1:ncell(r))
r2 <- raster(nrows=10, ncols=10)
r2 <- setValues(r2, 1:ncell(r))
St=stack(r,r1,r2)
idx <- seq(as.Date('2008-01-15'), as.Date('2008-1-17'), 'day')
SISmm <- setZ(St, idx)
hovmoller(SISmm, contour=FALSE, panel=panel.levelplot.raster,
          yscale.components=yscale.raster.subticks,
          interpolate=TRUE, par.settings=RdBuTheme)

This produces:

So I want the time to be on the X axis and latitude on the Y axis!

Answer 1

That layout is not implemented in the rasterVis::hovmoller method. Only the common arrangement (time on the y-axis and latitude/longitude on the x-axis) is available at the moment.

You can try a workaround using the most important parts of the function code. For your example, you have to create a RasterLayer with the latitude values. This RasterLayer is used by zonal to aggregate your RasterStack:

library('raster')

dirLayer <- init(SISmm, v='y')
z <- zonal(SISmm, dirLayer, FUN='mean', digits=2)

The result is a matrix which is converted to a data.frame to be displayed with lattice::levelplot.

## Time on the x-axis, latitude on the y-axis
dat <- expand.grid(y=z[,1], x=idx)
dat$z <- as.vector(z[,-1], mode='numeric')

levelplot(z ~ x*y, data=dat,
          xlab='Time', ylab='Latitude',
          panel=panel.levelplot.raster,
          interpolate=TRUE,
          par.settings=RdBuTheme())