[Numpy-discussion] ANN: MaskedArray as a subclass of ndarray?-?followup

Robert Kern robert.kern at gmail.com
Fri Jan 19 14:00:44 EST 2007

Stefan van der Walt wrote:

> A "nice C level api" sounds like the definition of oxymoron :) Why
> would we argue for more C than absolutely necessary in a Python-based
> library?

Well, it's more often absolutely necessary than you might think. Any common
operation on the array should be written in C to avoid the Python function call
overhead. We learned that with recarrays. The a.column_name notation (equivalent
to a['column_name']) in implemented in a Python method __getattribute__. If you
happen to use this in a tight loop, you'll find that __getattribute__ is a

Unfortunately, the methods you might want to add or override on an ndarray
subclass are going to be the ones that you would want to be efficient.

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
 that is made terrible by our own mad attempt to interpret it as though it had
 an underlying truth."
  -- Umberto Eco

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