Hi Alan, Yes, thank you. Shared elements is the out come I need. The problem I have now is how to return the shared elements back into the numarray.array([]) constructor. Numarray doesn't recognize the sets.Set([]) constructor as a python numeric type. I actually don't see any functionality/methodology to convert a sets.Set([]) back into any of the sequence types. I am also don't understand why this ability, to retrieve shared elements of two unequal arrays, is not an inherent numarry function/method. Thank you for your initial direction to the sets module, Kevin __________________________________ Do you Yahoo!? The all-new My Yahoo! - Get yours free! http://my.yahoo.com