Is it possible in R to create a color key like the one below? (this one comes from the software Grid Analysis and Display System - Grads).
There are two features that I can't reproduce in R:
- The sequence is non linear however it is displayed as if
- Values bigger than 200 are grey / Values smaller than 0 are white
I'm using levelplot from rastervis that plots rasters using the lattice levelplot:
require(raster) require(rasterVis) set.seed(200) X = seq(-40,0,by=1) Y = seq(-60,-40,by=1) grid = expand.grid(list(X=X,Y=Y)) Z = rnorm(nrow(grid),mean=10,sd=100) data = data.frame(grid,Z) r = rasterFromXYZ(data) mapTheme <- rasterTheme(region=c('#EEF7FA','#D6F8F7',"#BEDAFF",'#5DA4FF',"#0000FF","#D4F9E2","#00FF7F","#008000","#FFFF00","#FFD27F", "#FFB732" ,"#EE7600", "#D53E4F","#FF6A6A")) my.at = c(0,1,5,10,15,20,25,30,40,50,75,100,150,200) myColorkey <- list(at=my.at, space="bottom", labels=list(at=my.at)) p=levelplot(r, par.settings=mapTheme,at = my.at, colorkey=myColorkey,margin=F) print(p)
The result:
As you can see, both values smaller than 0 and bigger than 200 are white, I've no idea how to set values bigger than or smaller than a certain value to appear as a specific color. Morover, how can I make the space between consecutive thick marks in the color key to have the same size although the intervals are not the same?
This is a workaround for equally sized intervals for non linear sequences:
library(raster) library(rasterVis) set.seed(200) X = seq(-40,0,by=1) Y = seq(-60,-40,by=1) grid = expand.grid(list(X=X,Y=Y)) Z = rnorm(nrow(grid),mean=10,sd=100) data = data.frame(grid,Z) r = rasterFromXYZ(data) mapTheme <- rasterTheme(region=c('#EEF7FA','#D6F8F7',"#BEDAFF",'#5DA4FF',"#0000FF","#D4F9E2","#00FF7F", "#008000","#FFFF00","#FFD27F", "#FFB732" ,"#EE7600", "#D53E4F","#FF6A6A")) my.at=c(0,1,5,10,15,20,25,30,40,50,75,100,150,200) my.brks=seq(0, 200, by=15) myColorkey <- list(at=my.brks, labels=list(at=my.brks, labels=my.at), space="bottom") p=levelplot(r, par.settings=mapTheme, at=my.at, colorkey=myColorkey, margin=F) print(p)
This could be a solution for values smaller 0 and greater than 200:
library(raster) library(rasterVis) set.seed(200) X = seq(-40,0,by=1) Y = seq(-60,-40,by=1) grid = expand.grid(list(X=X,Y=Y)) Z = rnorm(nrow(grid),mean=10,sd=100) data = data.frame(grid,Z) r = rasterFromXYZ(data) mapTheme <- rasterTheme(region=c('white','#EEF7FA','#D6F8F7',"#BEDAFF",'#5DA4FF',"#0000FF","#D4F9E2","#00FF7F", "#008000","#FFFF00","#FFD27F", "#FFB732" ,"#EE7600", "#D53E4F","#FF6A6A", "gray")) max(values(r)) min(values(r)) my.at=c(min(values(r)), 0,1,5,10,15,20,25,30,40,50,75,100,150,200, max(values(r))) my.brks=seq(0, 200, by=13) myColorkey <- list(at=my.brks, labels=list(at=my.brks, labels=c(-276,0,1,5,10,15,20,25,30,40,50,75,100,150,200, 388)), space="bottom") p=levelplot(r, par.settings=mapTheme, at=my.at, colorkey=myColorkey, margin=F) print(p)
Your colors are not progressing from light to dark. You can use the RColorBrewer package to fix this.
library(RColorBrewer) reds = brewer.pal(5, "YlOrRd") greens = brewer.pal(3, "Greens") blues = brewer.pal(5, "Blues") mapTheme <- rasterTheme(region=c('white', blues, greens, reds, "gray"))
