"Fredrik Lundh" <fredrik at pythonware.com> wrote in message
news:mailman.379.1160661911.11739.python-list at python.org...
> Paul McGuire wrote:
>>> My original question was in response to your post, that sort() wasn't
>> required but only a temp variable. I am very interested in seeing your
>> solution that does not require the data to be sorted. (This is not just
>> an academic exercise - given a large historical data set, sorting the
>> data is one of the costliest parts of computing the median, and I would
>> greatly appreciate seeing an alternative algorithm.)
>> if you absolutely definitely cannot afford to modify or copy the input
> data set, but can
> read the data sequentially multiple times reasonably fast, you can do
> what's basically a
> binary search for the median, by counting how many values you have that's
> above or
> below the current guess, and repeating until you find the right value.
> see e.g.
>>http://ndevilla.free.fr/median/median/src/torben.c>> </F>
Thanks!
-- Paul
