我想将显示valuesof 的标签添加latitudinal zonal averages到levelplot'sgray margin。在以下示例中,min和的max值latitudinal means分别为286和751。adding an axis对此信息有何建议margin? 
 
  
library(raster)
library(rasterVis)
r <- raster(system.file("external/test.grd", package="raster"))
levelplot(r, at=seq(100, 1850, by = 250))
# calculating the latitudinal means
rows <- init(r, v='y')
yAve <- zonal(r, rows, fun='mean',na.rm=TRUE)  
summary(yAve)   
