Thanks Matt!
That was easy. It only took about a minute to sample 10,000 points
from 30 layers into a single shapefile, and from there save to
csv. I'll investigate using gpkg directly from R in future.
Best,
Tyler
Matt Boyd writes:
Hi Tyler,
the point sampling tool plugin will allow you to select multiple
rasters to
sample from and output to the same file. It also allows you to
save the
results in a number of different formats (geopackage, csv and
shapefile).
If you've got access to python in your version of R then
geopandas can read
geopackage files directly, I find that a lot more useful than
csv.
I use this workflow. The slowest part is the point sampling
depending on
the number and size of rasters and points.
Matt
On Tue, May 5, 2020 at 6:49 AM Tyler Smith <[email protected]>
wrote:
Hi,
I have 30 raster layers, and I need to sample 10,000 random
points
from each layer (using the same set of points each time). I
think
my options are:
1. Create a virtual raster, and sample. This has the downside
that
the identify of the 30 layers will be replaced by generic
'band1',
'band2' labels.
2. Sample the layers directly, using a batch process. This has
the
downside that it appears to output to gpkg format, and creates
30
separate files. I will need to open each of these files, export
the points they contain to csv, and then combine the into a
single
table in R for analysis.
Is there a way to create a virtual raster that retains the
layer
names in the stack? Alternatively, can I bulk sample multiple
rasters and have the output combined in a single table?
Thanks,
Tyler
--
Tyler Smith
plantarum.ca
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plantarum.ca
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