[Numpy-discussion] Condensing array...

Gael Varoquaux gael.varoquaux@normalesup....
Fri Feb 25 03:42:39 CST 2011

On Fri, Feb 25, 2011 at 10:36:42AM +0100, Fred wrote:
> I have a big array (44 GB) I want to decimate.

> But this array has a lot of NaN (only 1/3 has value, in fact, so 2/3 of 
> NaN).

> If I "basically" decimate it (a la NumPy, ie data[::nx, ::ny, ::nz], for 
> instance), the decimated array will also have a lot of NaN.

> What I would like to have in one cell of the decimated array is the 
> nearest (for instance) value in the big array. This is what I call a 
> "condensated array".

What exactly do you mean by 'decimating'. To me is seems that you are
looking for matrix factorization or matrix completion techniques, which
are trendy topics in machine learning currently.

They however are a bit challenging, and I fear that you will have read
the papers and do some implementation, unless you have a clear
application in mind that enables for simple tricks to solve it.


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