title: Is there a way to customly define a color in the levelplot function in the lattice package when already using a col.region?
body: <p>im using the levelplot function of the lattice-package to display the results in a simulation study of detecting serial independance in simulated AR-time series under different alternatives. As a color sheme im using the magma colors of the viridis-package and now im trying to highlight those alternatives, where the rejection-rate is lower than 0.05 in an additional color to increase the visiability of those alternatives.
  Is there anyway to specify this in the levelplot function?</p>
  <p>Heres a try on a minimal example:</p>
  <pre><code>library(lattice) 
  library(viridis)
  
  
  Grid=expand.grid(mean=seq(0,0.5,by=0.01),rho=seq(0,0.5,by=0.01))
  
  X=seq(1,dim(Grid)[1])
  Rej=sapply(X, function(X) sum(Grid[X,]$mean,Grid[X,]$rho))
  Grid$Rej=Rej
  
  levelplot(Rej ~ mean*rho, data=Grid ,layers=1,col.regions=magma, at=seq(0,1,by=0.05))
  </code></pre>
  <p>Here im looking to have the values below 0.05 in another color than black, because its hard to spot if the alpha-level is met.</p>
  <p>Thanks in advance,
  Hendrik</p>