Hi,
On Thu, Oct 13, 2011 at 2:05 PM, Bailey, Daniel <bai...@spu.edu> wrote:
> Thank you Sarah. I tried your suggestion, and if I coerce it into a normal
> data.frame, that method works. But if you've already made the data into a
> SpatialPixelsDataFrame and run coordinates (both from the package "sp") so
> that the columns "x" and "y" become a single column "coordinates" with the
> format (0, 17) for x and y, how do you then call or manipulate data at a
> specific location?
>
> The following:
> e[e$coordinates==(0,17),]
> Doesn't work.
They "don't become a single column" but rather a single matrix with
two columns, and (0, 17) isn't the correct way to specify a vector.
You can identify particular coordinates using the form I offered
earlier, and then use that to subset the data slot of your SGPF.
Using built-in data:
library(sp)
data(meuse.grid)
m = SpatialPixelsDataFrame(points = meuse.grid[c("x", "y")], data = meuse.grid)
m@data[coordinates(m)[,"x"] == 181100 & coordinates(m)[,"y"] == 333660,]
There ought to be a more elegant way to match coordinates (other than
the do.call() and paste() approach), but I'm not sure what it is.
Sarah
--
Sarah Goslee
http://www.functionaldiversity.org
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