I use extract() to get bilinear interpolated points out of my raster-object. Is there a way to show intermediate steps of the interpolation? I would be interested in the coordinates and values of the nearest four grid-points and the distances to my interpolation point.
With r = raster(...) and spdf = SpatialPointsDataFrame() my function call is the following:
out <- extract(r, spdf, method="bilinear")