Hi, what about numpy? import numpy a = numpy.ones((10,),dtype=numpy.bool) I = [1,3,8] a[I]=False print a gives: [ True False True False True True True True False True] Almar -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-list/attachments/20081203/3360d963/attachment-0001.html>