Combining non-overlapping binary rasters with ArcGIS Raster Calculator?

Question

The issues I keep seeing depend on unique combinations of values.

I have three rocktype raster layers for area and they are edge-to-edge (they do not overlap). They each have "VALUE" fields and "COUNT" fields. There's one row of data for each attribute table where "VALUE"=1 where the rock type exists. I guess this is like mask.

What I need to do is combine these three rasters into one with raster calculator using this logic.

rocktype1==1, output value=1

rocktype2==1, output value=2

rocktype3==1, output value=3

Here's what I've tried:

Con("rocktype2"==1, 2) | Con("rocktype1"==1, 1) | Con("rocktype3"==1, 3)
Con("paleo"==1, 2, Con("precamb"==1, 1, Con("tert_quat"==1, 3))) 
Combine(["rocktype2","rocktype1","rocktype3"])
rocktype1 + rocktype2 + rocktype3

I continuously get a blank output raster. What am I doing wrong here?

I'm using ArcMap 10.3.

Answer 1

The raster calculator is working a different way.

First you need to declare your OutRaster that will be saved:

OutRas = Con(...)

Your expression may probably look like this (like your second try, but not sure why you set other names there):

OutRas = Con("rocktype1"==1,1,Con("rocktype2"==2,2,Con("rocktype3"==1,3)))

Answer 2

As per comment by FelixIP, this expression worked for me:

~IsNull("precamb")+2*(~IsNull("paleo"))+3*(~IsNull("tert_quat"))