[Numpy-discussion] Overload binary operators with custom array type

Travis Oliphant oliphant.travis at ieee.org
Fri Jan 12 16:44:51 EST 2007

Adam Jenkins wrote:
> Timothy Hochberg <tim.hochberg <at> ieee.org> writes:
>>You want __array_priority__; add an attribute __array_priority__ to your
> array-like object and set it's value to, say, 10 and ndarrays will defer to your
> object.
> Thank you very much.  I had seen the __array_priority__ property mentioned in
> the Numpybook, but it's only documented there as being used to decide which
> operand's type the result of an operation should be converted to, so I didn't
> realize it would also be used to decide which operand to defer the operation to.
> I just tried it, and it does solve the problem for the mathematical operators
> like + and -, but doesn't seem to work for the comparison operators.  That is,
> if I write
> lhs < rhs
> where lhs is a numpy.ndarray and rhs is a myarray, numpy still treats rhs as a
> scalar and tries to compare each element of lhs to rhs, even though I set
> myarray.__array_priority__.  Is this intentional that the comparison operators
> ignore __array_priority__, or just a bug in ndarray?  

Probably could be considered a bug.

What does

less(lhs, rhs)



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