On Thu, Feb 20, 2020 at 12:41 PM Steve Jorgensen <stevej@stevej.name> wrote:
Christopher Barker wrote:
> > Perhaps the OP wanted the internal array size initialized, but not used.
> Currently the internal array will automatically be reallocated to grow as
> needed. Which could be a performance hit if you know it’s going to grow
> large.
> But frankly, it would be a rare case where this would be noticeable.
> -CHB

Maybe uncommon, but I don't know about rare. Let's say you want to perform list-wise computations, making new lists with results of operations on existing lists (similar to numpy, but maybe trying to do something numpy is unsuitable for)? You would want to pre-allocate the new array to the size of the operand arrays.

Strong +1 for an array.zeros() constructor, and/or a lower level array.empty() which doesn't pre-fill values.

A use case that came up for me recently is efficiently allocating and filling an object that satisfies the buffer protocol from C/C++ without requiring a NumPy dependency. As far as I can tell, there is no easy way to do this currently.