[Numpy-discussion] [ANN] Nanny, faster NaN functions

Keith Goodman kwgoodman@gmail....
Fri Nov 19 21:59:55 CST 2010


On Fri, Nov 19, 2010 at 7:51 PM,  <josef.pktd@gmail.com> wrote:
>
> does this give you the correct answer?
>
>>>> 1>np.nan
> False
>
> What's the starting value for amax? -inf?

Because "1 > np.nan" is False, the current running max does not get
updated, which is what we want.

>> import nanny as ny
>> np.nanmax([1, np.nan])
   1.0
>> np.nanmax([np.nan, 1])
   1.0
>> np.nanmax([np.nan, 1, np.nan])
   1.0

Starting value is -np.inf for floats and stuff like this for ints:

cdef np.int32_t MININT32 = np.iinfo(np.int32).min
cdef np.int64_t MININT64 = np.iinfo(np.int64).min

Numpy does this:

>> np.nanmax([])
<snip>
ValueError: zero-size array to ufunc.reduce without identity

Nanny does this:

>> ny.nanmax([])
   nan

So I haven't taken care of that corner case yet. I'll commit nanmax to
github in case anyone wants to give it a try.


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