[Numpy-discussion] missing data discussion round 2

[Nathaniel Smith]

On Tue, Jun 28, 2011 at 4:37 PM, Mark Wiebe <mwwiebe at gmail.com> wrote:
> I've nearly finished this parameter, and decided to call it 'where' instead,
> because it is operating like an SQL where clause. Here if neither a nor b
> are masked array it will only modify those values of b where the 'where'
> parameter has the value True.

Probably a good idea, since in the current NEP, masks do not have a
'where' clause effect (at least for reduction operations), unless you
pass skipna=True. So calling it mask= would be a bit confusing :-)

So if I understand right,
  f(a, b, where=c)
is basically an optimized (copy-avoiding) version of
  f(a[c], b[c])
? Except, in this case, c must be a boolean array of exactly the right
shape, you don't support broadcasting or integer arrays or slices,
etc.?

-- Nathaniel