Graduated Colors Renderer Errors

Question

I have this small code to change a feature layer's symbology. I'm referencing this help doc.

When I try to change the break count I get a RuntimeError. And when I try to identify the classification field I don't seem to find it. Using a print statement, I identify other properties but not the field. The only thing i can think of is possibly because this field is set to a custom expression:

for lyr in m.listLayers():
    if lyr.isFeatureLayer:
        sym = lyr.symbology

if hasattr(sym, 'renderer'):
            #type of renderer 
            if sym.renderer.type == 'GraduatedColorsRenderer':
                #sym.renderer.breakCount = 4 -RuntimeError: Invalid breakCount 4
                print('break count: {}
method: {}
field: {}'.format(sym.renderer.breakCount, 
                                                                        sym.renderer.classificationMethod, 
                                                                        sym.renderer.classificationField))

prints:
break count: 5
method: ManualInterval
field:

JaredPilbeam2 · Accepted Answer

The classification field has to be a number in order for the renderer to recognize it. It validated both with float and double. It will not work with text fields. I'm in contact with an ESRI analyst who is looking into why that is.