[Numpy-discussion] MaskedArray __setitem__ for Record Values
Alexander Michael
lxander.m@gmail....
Fri Feb 15 09:51:04 CST 2008
I am attempting to work with field dtypes (i.e. record arrays) as
MaskedArrays. I don't want to use MaskedRecords because I want the
mask to apply to the whole record since the first field is primary and
the rest are "tag along" values associated with the primary data
value. The numpy.ndarray supports the ability to set a record with a
(heterogenous) sequence, but MaskedArray does not:
>>> import numpy
>>> from numpy import ma
>>> d = numpy.empty((5,4), dtype=[('value', float),('source', int)])
>>> a = ma.MaskedArray(d, mask=True, fill_value=(0.0,0))
>>> a[0,0] = (10.0, 1)
numpy\ma\core.py in __setitem__(self, indx, value)
1359 return
1360 #....
-> 1361 dval = getdata(value).astype(self.dtype)
1362 valmask = getmask(value)
1363 if self._mask is nomask:
TypeError: expected a readable buffer object
I suggest replacing " dval = getdata(value).astype(self.dtype)" with
something along the lines of:
dval = None
if self.dtype.fields is None:
dval = getdata(value).astype(self.dtype)
else:
dval = value
but I do not understand all of the activity in the __setitem__ method,
so this may be too naive
a fix (but it *appears* to work).
Thanks,
Alex
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