[Numpy-discussion] behavior of masked arrays

Pierre GM pgmdevlist@gmail....
Fri Mar 7 11:37:55 CST 2008


On Friday 07 March 2008 12:25:13 Giorgio F. Gilestro wrote:
> Ok, I see, thank you Pierre.
> I thought scipy.stats would have been a widely used extension so I
> didn't really consider the trivial possibility that simply wasn't
> compatible with ma yet.

Partly my fault here, as I should have ported more functions. <rant>Blame the 
fact that working on an open-source project doesn't translate in 
publications, and that my bosses are shortening the leash...</rant>. 
Note that most (all?) of the functions in scipy.stats never supported masked 
arrays in the first place anyway. Now that MaskedArray is just a subclass of 
ndarray, porting the functions should be easier.

> I had a quick look at the code and it really seems that ma handling can
> be achieved by replacing np.asarray with np.ma.asarray, and some
> functions with their methods (like ravel) here and there.

Yes and no. I'd prefer to use numpy.asanyarray as to avoid converting ndarrays 
to masked arrays, and use methods as much as possible. Of course, there's 
gonna be some particular cases to handle (as when all the data are masked), 
but that should be relatively painless.

Another issue is where to store the new functions: should we try to ensure 
full compatibility of scipy.stats with masked arrays? Create a new module 
scipy.mstats instead, that we'd fill up with time ? I'd be keener on the 
second approach, as we could move most of the functions currently in 
numpy.ma.m(ore)stats to this new module, and that'd probably less work at 
once...


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