[Tutor] Faster procedure to filter two lists . Please help

[Alan Gauld]

> It this correct? Python lists are not linked-lists (as in Scheme,
for
> example). They are more like arrays (or vectors in C++/Java) with a
> little more sofistication built into them to allow, for example, to
> amortize over time a sequence of append operations. But in a
nutshell,
> len is actually a field in the underlying C object so len() is a
> constant (O(1)) and as-fast-as-it-can-be operation.
>
> Someone correct me, please, If I'm wrong.

I thought that too, but after a recent thread when I said
the same I got an off list mail assuring me that len() was
calculated at run time by iterating over the collection!

I guess I should go and look at the code!
However in either case missing out the two function calls
to len() would help improve the speed...

Alan G.