Is it safe to write A = [x for x in A if x in U]
or is that undefined? I understand that the slice operation can be used to make a temporary copy, so I could write A=[x for x in A[:] if x in U] but I've just copied that without any understanding. Steve. "bambam" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] > That looks good, and perhaps a difference operator > would be too simple to be useful anyway. > > Steve. > > "Mikael Olofsson" <[EMAIL PROTECTED]> wrote in message > news:[EMAIL PROTECTED] >> >> >> bambam wrote: >>> >>> In this case it doesn't matter - my lists don't contain >>> duplicate elements this time - but I have worked with lists in >>> money market and in inventory, and finding the intersection >>> and difference for matching off and netting out are standard >>> operations. >> >> I would use a list comprehension for that case: >> >> A = ['a','b','c','a','c','d'] >> U = ['a','b','e'] >> B = [x for x in A if x in U] >> >> The result would be B==['a','b','a'] >> >> /MiO > > -- http://mail.python.org/mailman/listinfo/python-list
