On Tue, Sep 25, 2012 at 12:31 PM, Sturla Molden
On 25.09.2012 11:38, Nathaniel Smith wrote:
Implementing a ring buffer on top of ndarray would be pretty straightforward and probably work better than a linked-list implementation.
Amazingly, many do not know that a ringbuffer is simply an array indexed modulus its length:
foo = np.zeros(n) i = 0 while 1: foo[i % n] # access ringbuffer i += 1
Good trick, but to be reliable I think you need to either be willing for i to overflow into a long (arbitrary width) integer, or else make sure that i is an unsigned integer and that n is 2**k where k <= sizeof(i)? Just doing i %= n on each pass through the loop might be less error-prone.
Also, instead of writing a linked list, consider collections.deque. A deque is by definition a double-ended queue. It is just waste of time to implement a deque (double-ended queue) and hope it will perform better than Python's standard lib collections.deque object.
The original poster is using collections.deque now, but wants a version that supports efficient vectorized operations. -n