Mapping cells from dataframe constructed in raster
Hi Janice, That works but seems much more complicated than need be. I think you should read the vignette that comes with the raster package: http://cran.r-project.org/web/packages/raster/vignettes/Raster.pdf Here is a simpler approach library(raster) s <- stack(system.file("external/rlogo.grd", package="raster")) # create a matrix m <- as.matrix(s) # add a column with the cell numbers m <- cbind(cell=1:ncell(s), m) # it seems that in your case this is not needed because you used # write.csv (which adds the cellsnumbers (rows in matrix) and then read.csv to accomplish # the same # for this example, I take a random sample of 100 cells set.seed(0) x <- sample(m[,1], 100) # create a RasterLayer template from the RasterStack r <- raster(s) # assign values to cells 'x' r[x] <- 1:length(x) plot(r) Next time you ask a question provide a self-contained example like Andrew's or this one, which makes it much easier to answer. Robert
On Thu, May 2, 2013 at 9:20 AM, Janice Lee <janice.jlsh at gmail.com> wrote:
Dear all,
I would appreciate anyone's help on this.
I constructed a dataframe from several raster layers and compiled these
layers using the 'stack' and 'brick' function in 'raster' package
s <- stack(r1,r2,r3,r4,r5)
b <- brick(s)
I converted this into a matrix and stored this as a dataframe:
mb <- as.matrix(b)
write.csv(mb,"C:/Source/mb.csv")
This new dataframe (mb) lists all the cells as rows and all the attributes
in my raster layers (r1-r5) as columns
The first column in mb also provides a number to each cell which I assume
acts as a form of identification number to every grid cell
I used mb in an R-coded model which simulates land cover change, in which I
selected the most suitable cells for land use conversion
My final dataframe (df) has a lower number of rows compared to mb but has
preserved the identification number of each grid cell.
My question is: Can I map out the cells in df by tracing its identification
number back to the original dataframe mb?
I have been trying to figure this out and will appreciate any suggestions.
Many thanks and best regards,
Janice Lee
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