How can I constrain my plot to the extent of the raster image?

Question

I am currently trying to create a multi-panel plot to display six raster images (3,2) using par() and plot(raster()). When I plot the rasters though, R is displaying the Y bounds far beyond what is necessary, resulting in lots of wasted space. How can I adjust this? When, I run extent() on the raster images themselves, the extent is correct.

a<-raster("file.tif")
...and so on to f.

par(mfrow=c(2,3))
plot(a)
plot(b)
plot(c)
plot(d)
plot(e)
plot(f)

Answer 1

Possibly a duplicate of this post. For some reason setting

plot(a,ext=extent(a),xaxs="i",yaxs="i")

does not work properly. xaxs,yaxs are internal variables in R that set a margin on data link. The documentation of the raster library says the above method should work. Try:

spplot(a)

that worked for me

Answer 2

You control the size of the plot area, plot(raster) just follows your lead. So set it to something you like --- that makes sense given the dimensions of the plots you are making. How you do that depends what "device" you plotting on and whether you use Rstudio or not. See e.g. ?png or dev.new(width=5, height=4). Or, in Rgui, resize manually and then plot again.

Answer 3

1. As Gevaert mentioned, I think this has been asked before, but I'll respond to this post since it's fairly recent.

2. I think Robert above made a good point about how the plot will stretch to the window.

Still, I found that raster::plot's documentation indicates that you can specify the plotting window and in my experience it has zero effect. Instead it will always assume the extent of the raster you give it.

My suggested workaround is to first draw your desired plot window with blank object then add the raster plot to this window.

my_window <- extent(-83,-82.85,28,28.2)
plot(my_window, col=NA)
plot(my_raster, add=T)

For me, this achieves what I'm after. The caveat is if you're plotting a stack or brick, the add functionality doesn't work in my experience. The solution is to use subset, like plot(subset(my_brick,4), add=T)

Answer 4

For me the following works:

extent(a) <- c(-180, 180, -180, 180)
crs(a) <- NULL
plot(a)

I do crs(a) <- NULL to avoid a warning.

Answer 5

  box=extent(my_raster)
  yxscale=(box@ymax-box@ymin)/(box@xmax-box@xmin)
  xsize=3 # in inches
  ysize=xsize*yxscale
  par(pin=c(xsize,ysize)) # to have a plot extenting to the limits of 
                            the raster
  plot(my_raster)