Using Null Values in Raster To NumPy?

Question

I am trying a convert a raster dataset [a simple 4 x 4] into a numpy array using RasterToNumPyArray. Here is my sample raster dataset:

RasterToNumPyArray however, returns zero for Null values:

inRaster = "Slope_NULL"

# Create a Raster Object and get its lowerleft
aRObject = arcpy.Raster(inRaster)
lowerLeft = aRObject.extent.lowerLeft

print aRObject.noDataValue

# Create a numpy array of the Raster Object
anArray = arcpy.RasterToNumPyArray(aRObject) 
print anArray

and I get:

I am wondering if there is a way that I could get None or NaN instead of zero in my array?

I know I can change the Nodata to a value using nodata_to_value, however, RasterToNumPyArray syntax is explaining that the default value is None, and it is important for me to have None and not zeros in my array.

How can I have None or NaN [I am not sure which one is better supported in numpy] in my array?

Answer 1

I think what you are looking for is NAN in Numpy module:

import numpy as np
arcpy.RasterToNumPyArray(inRaster, nodata_to_value= np.NAN)

Also see for here for other constants defined in Numpy.