sum_by_n should always be floordiv
sum_by_n should always be floordiv

schmidtc/pysal,sjsrey/pysal_core,schmidtc/pysal,pastephens/pysal,jlaura/pysal,lanselin/pysal,ljwolf/pysal_core,hasecbinusr/pysal,sjsrey/pysal,hasecbinusr/pysal,sjsrey/pysal_core,lixun910/pysal,jlaura/pysal,weikang9009/pysal,lixun910/pysal,pysal/pysal,pedrovma/pysal,TaylorOshan/pysal,jlaura/pysal,pastephens/pysal,TaylorOshan/pysal,ljwolf/pysal_core,hasecbinusr/pysal,ljwolf/pysal,ljwolf/pysal,TaylorOshan/pysal,ljwolf/pysal_core,pastephens/pysal,lixun910/pysal,sjsrey/pysal_core,ljwolf/pysal