sample_raster {graph4lg} | R Documentation |
Sample points or patches on a categorical raster layer
Description
The function samples points or patches on a categorical raster layer.
Usage
sample_raster(
raster,
class,
nb_pts,
dist_min = 0,
edge_size = 0,
by_patch = TRUE,
neighborhood = 8,
surf_min = 0,
prop_area = TRUE,
step_max = 1000,
output = "df",
desc = TRUE
)
Arguments
raster |
A RasterLayer object corresponding to a categorical raster layer |
class |
An integer value or vector with the value(s) corresponding to the code values of the raster layer within which points will be sampled. |
nb_pts |
An integer value indicating the number of points to be sampled |
dist_min |
An integer value indicating the minimum distance separating the sampled points (default = 0). |
edge_size |
An integer value indicating the width of the edge of the raster layer which is ignored during the sampling (default = 0). It prevents from sampling in the margins of the study area. |
by_patch |
A logical value indicating whether contiguous patches with cells having the same code value are delineated prior to sampling (default = TRUE). It prevents from sampling several points in the same contiguous patch. |
neighborhood |
An integer value indicating which cells are considered
adjacent when contiguous patches are delineated (it should be 8
(default, Queen's case) or 4 (Rook's case)). This parameter is ignored
when |
surf_min |
An integer value indicating the minimum surface of a patch
considered for the sampling in number of raster cells. This parameter is used
whatever the |
prop_area |
A logical value indicating whether sampling in large patches
is more likely (default = TRUE). If |
step_max |
An integer value indicating how many sampling steps are performed to identify a point set satisfying all the conditions before returning an error. |
output |
A character string indicating the type of returned output:
|
desc |
A logical value indicating whether the result should be
described or not (default = FALSE). If |
Value
A list of object(s) with one or several elements according to the
output
and desc
arguments.
Author(s)
P. Savary