Is there a random sampling of raster using R?

Is there a random sampling of raster using R?

Random sampling of raster using R? Is there a straightforward way of randomly sampling a raster so that the output of the process is a raster? I’m using an example that I found on the r-sig-geo list and I have also tried the sampleRandom function in the raster package.

How to select random points from a raster file?

I had been using the raster package sampleRandom (raster,n, na.rm=TRUE, xy=TRUE) to select random points before extracting the data from my raster object but this works without replacement.

Is it possible to sample random points from only the non-NA region?

I understand that it is possible to sample within the region and then use the raster layer as a mask to remove from the sampled points those which fall within the NA region of the layer, but, in doing this, the number of background points left over is less than that which was user-specified within the spsample function.

Which is the S4 method for samplerandom in raster?

## S4 method for signature ‘Raster’ sampleRandom (x, size, na.rm= TRUE, ext= NULL, cells= FALSE, rowcol= FALSE, xy= FALSE, sp= FALSE, asRaster= FALSE.) logical. If TRUE (the default), NA values are removed from random sample Extent object. To limit regular sampling to the area within the extent logical.

Which is a vector or matrix in raster?

A vector, matrix (if cells=TRUE or x is a multi-layered object), or a SpatialPointsDataFrame (if sp=TRUE )

How to extract values from rasters at location of points in R?

I recommend you to add these lines of code after your read.table () statement in order to convert presencias dataframe to a SpatialPointsDataFrame object (just refine the names of the columns containing x and y coordinates if they differ from my example). To provide a reproducible example, I try to open up the scope of my answer a little more.

How to calculate sample points in spatial features?

Sample points on or in (sets of) spatial features. By default, returns a pre-specified number of points that is equal to size (if type = “random” and exact = TRUE) or an approximation of size otherwise. spatstat methods are interfaced and do not use the size argument, see examples. st_sample(x, size.)

How is sampling done in a spatial class?

When x is of a class deriving from Spatial-class for which no spsample-methods exists, sampling is done in the bounding box of the object, using spsample.Spatial. An overlay using over may be necessary to select the features inside the geometry afterwards. Sampling type “nonaligned” is not implemented for line objects.