Visualize negative/poitive data using levelplot in R
Hello, You did answer this same question at stackoverflow ( http://stackoverflow.com/q/28753126/964866) without letting us know about it. This post is worth reading if you really need to do cross-posting ( http://www.coderanch.com/how-to/java/BeForthrightWhenCrossPostingToOtherSites ): This practice may not be in the interests of the ranchers who might be responding to your posts. Many folks may find that they have wasted their time and effort. You certainly don't want to annoy those you want to help you, so you might want to make the experience as painless as possible. The best way to do something like this (without ticking people off) would be to let people know upfront that the crossposting is occurring. This makes the most sense if there's a respectable delay between posting in one forum and another, e.g: "I posted this question the other day in SomeOtherForum.com [link], but wasn't able to get a good answer, so now I'm asking here..." I have just posted a simple answer to your question which I reproduce here: In my opinion, you have two choices: 1. Use a different key for each graph. 2. Rescale the data to create a common scale. Because you need a single colorkey you should rescale the data. Although this document ( http://www.perceptualedge.com/articles/visual_business_intelligence/dual-scaled_axes.pdf) is about time series, it gives good advices about this issue. Best, Oscar. ----------------------------------------------------------------- Oscar Perpi??n Lamigueiro Dpto. Ing. El?ctrica, Electr?nica, Autom?tica y F?sica Aplicada (ETSIDI-UPM) Grupo de Sistemas Fotovoltaicos (IES-UPM) URL: http://oscarperpinan.github.io 2015-02-26 22:43 GMT+01:00 Zilefac Elvis via R-sig-Geo < r-sig-geo at r-project.org>:
Hello,
I need your insigts on how to visualize/map data that spans negative and
positive values. I have 6 rasters which have been stacked together (s) and
will subsequently be plotted via levelplotfunction in R. Below are
the max and min values for each raster.39.2887, 53.09207 (min, max) # r1
-32.4956, -27.25534 (min, max)# r2
-14.37683, -11.37742 (min, max)# r3
9.512934, 13.60197 (min, max)# r4
-4.993901, -1.851784 (min, max)# r5
-8.190711, -5.104764 (min, max)# r6At the moment, I am able to produce my
map via:library(raster)
library(rasterVis)
library(colorRamp)
s <- stack(r1,r2,r3,r4,r5,r6)
themes2 <- colorRampPalette(c("darkred", "red3", "orange", "yellow",
"lightskyblue", "royalblue3", "darkblue"))(19)
myat =unique(seq(floor(min(s)) ,ceiling(max(s)),length.out=20))
myat=round(myat,digits = 0)#
#themes <- rasterTheme(region=rev(brewer.pal(11,'RdYlBu')))
myColorkey <- list(at=myat,space = "right",labels=list(cex=1,at=myat))
if (dev.cur() == 1) x11(width=18,height=18)
levelplot(s, layout=c(3, 2), index.cond=list(c(1, 3, 5, 2, 4,
6)),col.regions=themes2,
margin=FALSE,xlab=NULL,at =unique(seq(floor(min(s))
,ceiling(max(s)),length.out=20)),
par.strip.text=list(cex=0),colorkey=myColorkey,scales=list(alternating=F))NOTE:
I need a single colorkeyProblem: rasters with smaller vs larger values get
suppressed and the information on the map is not well visualized. How can I
visualize such data using levelplot with this large range?You can generate
6 rasters with values within the ranges shown above to give me further
clues.Thanks for your help! The colorkey must not be red to blue. Something
likehttp://iges.org/grads/gadoc/colorcontrol.html "The Default Rainbow
Palette" would do.
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