ToshiBoy, You might want to take a look at the filter() function, it can also be used for the kind of the thing you're doing.
http://docs.python.org/tut/node7.html#SECTION007130000000000000000 >>> B = range(1,27) >>> def test(b): ... if b*b in B: ... return True ... else: ... return False ... >>> A = filter(test, B) >>> A [1, 2, 3, 4, 5] Daniel On Sat, Jun 28, 2008 at 1:00 AM, ToshiBoy <[EMAIL PROTECTED]> wrote: > On Jun 28, 2:48 pm, Mel <[EMAIL PROTECTED]> wrote: > > ToshiBoy wrote: > > > I have two lists A and B that are both defined as range(1,27) I want > > > to find the entries that are valid for A = BxB > > [ ... ] > > > I get, as expected 1,4,9,16,25 printed out being the only members of B > > > where the condition is true, but when I print B I get: > > > > > [1, 2, 3, 4, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25] > > > > > 1 to 5 is correct, but why doesn't the remove method remove 7 and > > > above? What am I doing wrong here? > > > > Try this: > > > > A = range(1,27) > > B = range(1,27) > > C = [] > > > > for b in B: > > print "Trying", b > > if b*b in A: > > print b > > C.append (b) > > else: > > print "Removing", b > > B.remove(b) > > print 'B', B > > print 'C', C > > > > The essential problem is that your `B.remove`s are pulling the rug out > from > > under your `for b in B:`. There are ways to mess with B while you > iterate. > > Running though B backwards will do: `for b in B[::-1]:`, or iterating > over > > a copy of B: `for b in B[:]:` or `for b in list(B):`. Leaving B alone > and > > building up the desired items in C is probably simplest. > > > > Mel. > > Thank you, of course! :-) Didn't even think of that... that I was > modifying my iterators... > > Thank you > -- > http://mail.python.org/mailman/listinfo/python-list >
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