Description Usage Arguments Details Value Author(s) References See Also Examples
Draws an equi-probable unstratified Generalized Random
Tessellation Stratified (GRTS) sample from a SpatialLines*
object
1 | grts.line(x, n, over.n = 0)
|
x |
A |
n |
Sample size. The number of sample points to draw from |
over.n |
Over-sample size. The number of 'over-sample' points to draw
from |
This is a wrapper for the grts
function in package spsurvey
.
This simplifies calling grts
when equi-probable samples are
desired. It extends the allowable input frame types to SpatialLines
objects
(i.e., no attributes),
rather than just SpatialLinesDataFrame
objects. For more
complicated designs (e.g., variable probability, stratification), call
grts
directly.
A SpatialPointsDataFrame
containing locations in the GRTS sample, in
order they are to be visited. Attributes of the sample points (in the embedded data frame) are
as follows:
sampleID
: A unique identifier for points in the sample.
This encodes the GRTS ordering of the sample. The output object
comes pre-sorted in GRTS order.
If the sample becomes un-GRTS-ordered, resort
by sampleID
(i.e., samp <- samp[order(samp$sampleID),]
).
pointType
: A string identifying regular sample points (pointType=="Sample"
)
and over-sample points (pointType=="OverSample"
).
geometryID
: The ID of the line in x
onto which sample points fall.
The ID's of lines in x
are row.names(geometry(x))
.
Any attributes of the original lines (in x
) onto which sample points
fall.
Trent McDonald
Stevens, D. L. and A. R. Olsen (1999). Spatially restricted surveys over time for aquatic resources. Journal of Agricultural, Biological, and Environmental Statistics 4 (4), 415-428.
Stevens, D. L. and A. R. Olsen (2004). Spatially balanced sampling of natural resources. Journal of the American Statistical Association 99, 262-278.
grts.line
, grts.polygon
, spsample
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | ## Not run:
# Draw sample
## The following take > 5s
HI.sample <- grts.line(HI.coast,10,5)
# Plot
plot( HI.coast )
# Plot 'sample' locations
plot( HI.sample[ HI.sample$pointType == "Sample", ], pch=16, add=TRUE, col="red" )
# Plot 'over sample' locations
plot( HI.sample[ HI.sample$pointType == "OverSample", ], pch=1, add=TRUE, col="blue" )
## End(Not run)
|
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.