[Numpy-discussion] bug with with fill_values in masked arrays?

Chris Withers chris@simplistix.co...
Wed Mar 19 06:29:08 CDT 2008


OK, my specific problem with masked arrays is as follows:

 >>> a = numpy.array([1,numpy.nan,2])
 >>> aa = numpy.ma.masked_where(numpy.isnan(a),a)
 >>> aa
array(data =
  [  1.00000000e+00   1.00000000e+20   2.00000000e+00],
       mask =
  [False  True False],
       fill_value=1e+020)

 >>> numpy.ma.set_fill_value(aa,0)
 >>> aa
array(data =
  [ 1.  0.  2.],
       mask =
  [False  True False],
       fill_value=0)

OK, so this looks like I want it to, however:

 >>> [v for v in aa]
[1.0, array(data =
  999999,
       mask =
  True,
       fill_value=999999)
, 2.0]

Two questions:

1. why am I not getting my NaN's back?

2. why is the wrong fill value being used here?

cheers,

Chris

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            - http://www.simplistix.co.uk


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