The Spatial Analyst tools can be executed using the Spatial Analyst ArcPy module to perform raster analysis. Here we create a random sample of cells, create an empty raster and pipe the sum of rasters 1 and 2 (in the stack) based on the random sample cell index. How To: Perform raster calculation using ArcPy Summary. If you are wanting to apply a function to a limited random selection of cells, you could create a random sample of the raster that would be used as an index. Here is an example that grabs a random sample of n size, across the raster layers values and sums them. If you're working with a raster with an attribute table (and it sounds like you are), a better tool might be the Field Calculator, which can incorporate python scripts to process if/else statements. If you are wanting a random sample of the values across rasters, for every cell, you could write a function that is passed to calc.

In this case, rasters 1 and 3 in the stack would be the only ones summed.

I am going to take a few guesses on summing specified rasters in the stack, drawing a random sample, across rasters to be summed and finally, drawing a random sample of cells to be summed.įor a sum on specified rasters in a stack, you can just index what you are after in the stack using a double bracket. In the future, please try to be more clear on what your expected outcome is.īased on your code, I really don't know what you are getting at. Why are you coercing into arrays? You can easily collapse a raster into a vector but, that does not even seem necessary here.

Raster calculation