I have a dataset that consists of point coordinates and values
associated with the points. I want to be able to grid the values, and
then do calulations using the values using the various raster
functions. I am, however, finding this difficult to do. I have tried
a number of functions including
Thank you very much for this quick reply Dr. Bivand.
I am taking good notes of your suggestions.
I'm a little concern about your comments that my data are not a marked point
process and would like to verify with you a few points. You are correct that
my points - the catch positions are
Tara, I think you need to 'rasterize' function
library(raster)
r - raster(ncol=10, nrow=10)
x - c(-25, -148, 46, 23, 0, -69)
y - c(-45, 30, 20, -10, 50, -7)
value - c(1, 2, 3, 4, 5, 6)
# you can do this:
r1 - rasterize(cbind(x, y), r, value)
plot(r1)
# or
sp -
Arnaud,
You can (directly) do the same with Raster* objects what Roger did with sp
objects:
library(raster)
t-raster(ncol = 10, nrow = 10)
t[1:2,] - seq(1,10,1)
t[3:5,1:5] - seq(1,5,1)
t[6:8,6:10] - seq(6,10,1)
t[9:10,] - seq(1,10,1)
plot(t)
library(classInt)
zClass - classIntervals(values(t),
Hello everyone,
I've been exploring ways to clip a grid/raster with a polygon/shape file
in R but what I have seen so far seems more suited for relatively fine grids
and large polygons (e.g. many grids fall within each polygon).
I'm confronted with a relatively coarse data grid for the US (0.3
Thank you Robert. That worked perfectly. I had been missing the
proper structure in using the rasterize function.
Tara
On Sat, Sep 17, 2011 at 5:42 PM, Robert J. Hijmans r.hijm...@gmail.com wrote:
Arnaud,
You can (directly) do the same with Raster* objects what Roger did with sp
objects:
Nice problem:
library(raster)
cds1 - rbind(c(-100,91), c(-140,15), c(-10, 40), c(-140,-91))
lines - SpatialLines(list(Lines(list(Line(cds1)), 1)))
r - raster(ncols=50, nrows=45, xmx=10)
r - rasterize(lines, r)
rc - rowColFromCell(r, cellFromXY(r, rasterToPoints(r)))
west - tapply(rc[,2], rc[,1],
