[Numpy-discussion] automatically avoiding temporary arrays

srean srean.list at gmail.com
Wed Oct 5 07:11:15 EDT 2016


Thanks Francesc, Robert for giving me a broader picture of where this fits
in. I believe numexpr does not  handle slicing, so that might be another
thing to look at.


On Wed, Oct 5, 2016 at 4:26 PM, Robert McLeod <robbmcleod at gmail.com> wrote:

>
> As Francesc said, Numexpr is going to get most of its power through
> grouping a series of operations so it can send blocks to the CPU cache and
> run the entire series of operations on the cache before returning the block
> to system memory.  If it was just used to back-end NumPy, it would only
> gain from the multi-threading portion inside each function call.
>

Is that so ?

I thought numexpr also cuts down on number of temporary buffers that get
filled (in other words copy operations) if the same expression was written
as series of operations. My understanding can be wrong, and would
appreciate correction.

The 'out' parameter in ufuncs can eliminate extra temporaries but its not
composable. Right now I have to manually carry along the array where the in
place operations take place. I think the goal here is to eliminate that.
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