When using an array as a sequence in the map() an axis of the array got lost. from Numeric import * def Func(Data3d): print Data3d.shape Arr=reshape(arange(27),(3,3,3)) print Arr.shape a=map(Func,Arr) result: (3,3,3) (3,3) (3,3) (3,3) To me, being quite new with all this, it's somewhat unexpected. What is happening and how do I get the third axis back? TIA, Ingo