[Numpy-discussion] masked arrays and NaNs
Eric Firing
efiring at hawaii.edu
Wed Apr 6 15:53:05 EDT 2005
Travis,
I am whole-heartedly in favor of your efforts to end the
Numeric/numarray split by combining the best of both. I am encouraged by
the progress you have made, and by the depth and clarity of the
accompanying technical discussions. Thank you!
I am a long-time Matlab user in Physical Oceanography, and I have been
trying to find a practical way to phase out Matlab. One key is
matplotlib, which is coming along wonderfully. A second is the
availability of a Num* (or scipy.base) module that provides the
functionality and ease-of-use I presently get from Matlab. This leads
to a request which I suspect and hope is consistent with your present
plans: efficient handling of NaNs and/or masked arrays.
In Physical Oceanography, and I suspect in many other fields, data sets
are almost always full of holes. Matlab's ability to use NaN as a bad
value flag provides a wonderfully simple and efficient way of dealing
with missing or bad data values. A similar ease and transparency would
be good in scipy.base. In addition, or as a way of implementing
NaN-handling internally, it might be best to have masked arrays
incorporated at the C level--with the functionality available by
default--rather than bolted on as a pure-python package. I hope that
inclusion of __array_mask__ in the protocol means that this is part of
the plan.
Eric
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