scale - Controlling legend and colors for raster values in R (equivalent to Matlab's caxis)? -
i'm trying plot esri grid raster image of surface. i've figured out how make plot, not how control r's color scale.
# open necessary libraries library("raster", lib.loc="c:/users/sam/documents/r/win-library/2.15") library("rgdal", lib.loc="c:/users/sam/documents/r/win-library/2.15") library("ncdf", lib.loc="c:/users/sam/documents/r/win-library/2.15") # goal: select esri grid ascii file , plot image. infile <- file.choose("c:/users/sam/dropbox/wsc/class stuff/groundwater hydraulics/swb wibu/results") r <- raster(infile) # read in metadata esri output file, split relevant variables info <- read.table(infile, nrows=6) ncols <- info[1,2] nrows <- info[2,2] xllcorner <- info[3,2] yllcorner <- info[4,2] cellsize <- info[5,2] nodata_value <- info[6,2] xurcorner <- xllcorner+(ncols-1)*cellsize yurcorner <- yllcorner+(nrows-1)*cellsize # plot output data - whole model domain pal <- colorramppalette(c("purple","blue","cyan","green","yellow","red")) par(mar = c(5,5,2,4)) # margins each plot, room colorbars par(pin=c(5,5)) # set size of plots (inches) par(xaxs="i", yaxs="i") # set axes fit data plotted plot(r, xlim=c(xllcorner, xurcorner), ylim=c(yllcorner, yurcorner), ylab='utm zone 16 n northing [m]', xlab='utm zone 16 n easting [m]', col = pal(50)) an example of 'infile' this:
ncols 262 nrows 257 xllcorner 304055.000 yllcorner 4792625.000 cellsize 10.000 nodata_value -9999.000 42.4 42.6 42.2 0 42.2 42.8 40.5 40.5 42.5 42.5 42.5 42.9 43.0 ... 42.5 42.5 42.5 0 0 43.3 42.7 43.0 40.5 42.5 42.5 42.4 41.9 ... 42.2 42.7 41.9 42.9 0 0 43.7 44.0 42.4 42.5 42.5 43.3 43.2 ... 42.5 42.5 42.5 42.5 0 0 41.9 40.5 42.4 42.5 42.4 42.4 40.5 ... 41.9 42.9 40.5 43.3 40.5 0 41.9 42.8 42.4 42.4 42.5 42.5 42.5 ... ... the problem 0 values in data stretch color axis beyond what's useful me. can't post image because don't have enough reputation points, example here: http://i.stack.imgur.com/osde0.png
basically, tell r stretch color axis 25-45, rather 0-50. know in matlab use command caxis. r have similar?
i used dataset "volcano" generate raster object, , make code reproducible.
here 2 options can try:
1- plot
library(raster) library(rcolorbrewer) r = raster(volcano) #raster object cuts=c(100,150,160,170,180,190,200) #set breaks pal <- colorramppalette(c("white","black")) plot(r, breaks=cuts, col = pal(7)) #plot defined breaks 
2- ggplot
library(ggplot2) library(raster) library(rcolorbrewer) r = raster(volcano) #raster object #preparing raster object plot geom_tile in ggplot2 r_points = rastertopoints(r) r_df = data.frame(r_points) head(r_df) #breaks set column "layer" r_df$cuts=cut(r_df$layer,breaks=c(100,150,160,170,180,190,200)) #set breaks ggplot(data=r_df) + geom_tile(aes(x=x,y=y,fill=cuts)) + scale_fill_brewer("legend_title",type = "seq", palette = "greys") + coord_equal() + theme_bw() + theme(panel.grid.major = element_blank()) + xlab("longitude") + ylab("latitude") 
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