If you do not mind losing any leading sequence of a: another approach would be: (a:&~: (#;[EMAIL PROTECTED] # #) ]) mylist
If you do mind, you might use: (a:&~: (#;.1@(1&,)@[ # a:,#) ])&.(a:&,) mylist I believe that either of these would be faster, for large sequences, than the other proposed alternatives. (But I have not actually bothered to test, so I might be wrong.) -- Raul ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
