John Ladasky wrote:
Hi folks,

I am aware that numpy has its own discussion group, which is hosted at
gmane.  Unfortunately, I can't seem to get in to gmane today.

It is not hosted at GMane. It just has a GMane mirror.

  http://www.scipy.org/Mailing_Lists

In any case, I'm not sure whether I have a problem with numpy, or with
my understanding of the Python pickle module, so I'm posting here.

I am pickling numpy.ndarray objects to disk which are of type "float",
but which may include NaN in some cells.  When I unpickle these
objects and then test for the presence of NaN, the test fails.

The problem is that you are trying to use "is" to compare by Python object identity. Except for dtype=object arrays, the object identities of the individual elements that you extract from numpy arrays are never guaranteed. Usually, they will always be different. You need to use numpy.isnan() to determine whether an object is a NaN.

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco

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