Hi, I think you want to reform your lookup table into a 2 column matrix with columns from_value and to_value, and then use raster::reclassify()

The one thing that makes me hesitate is the lookup rule you describe. If a cell has a value of 20 then assign lut value m[20,1] So does that mean a cell value of 49 gets assigned m[40,10] ? What happens to a cell value of 3? These is no m[0,3]. Cheers, Ben > On Apr 10, 2018, at 12:45 PM, Thiago V. dos Santos via R-sig-Geo > <r-sig-geo@r-project.org> wrote: > > I have a large (7000x7000, 10-layered) raster stack whose values range from 0 > to 100. > > I need to modify the raster values using the a "lookup table" consisted of a > matrix which is 100 rows long by 10 cols wide, where the number of rows is > associated with the 0-100 value range of the raster and the number of columns > relates to the number of layers of the raster stack. > > The following code creates a toy example of my dataset: > > # Create raster stackr <- raster(ncol=50, nrow=50)s <- stack(lapply(1:10, > function(x) setValues(r, 1:ncell(r)))) > > # Create lookup tablem <- matrix(sample(100, 100*10, TRUE), 100, 10) > > Therefore, I need to loop through each cell of the raster and check its > value. For example, if the cell value is `20`, then the new value will be > reassigned from the 20th line and 1st column in the matrix. > > And so on for the 2nd raster stack layer and 2nd matrix column. And so on for > the remaining raster stack layers and matrix columns. > > Any ideas on how to do that? > > I know this sounds a bit cumbersome, but that's how a few ISRIC-WISE's soil > datasets are organized! > Greetings, -- Thiago V. dos Santos > Postdoctoral Research FellowDepartment of Climate and Space Science and > EngineeringUniversity of Michigan > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > Ben Tupper Bigelow Laboratory for Ocean Sciences 60 Bigelow Drive, P.O. Box 380 East Boothbay, Maine 04544 http://www.bigelow.org Tick Forecasting: https://eco.bigelow.org/ [[alternative HTML version deleted]] _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo