[SciPy-dev] Suppressing of numpy __mul__, __div__ etc

Dmitrey tmp50@ukr....
Sat Dec 12 09:09:19 CST 2009


hello all,  
I have class oofun (in a package FuncDesigner, that is already used by lots of people) where some operations on numpy arrays (along with Python lists and numbers) are overloaded, such as __mul__, __add__, __pow__, __div__ etc.  
There is a problem with numpy arrays: if I use a*f where a is array and f is oofun, it returns array with elements a[i]*f. Would it omit calling array.__mul__ and call only oofun.__rmul__, like it is done in numpy.matrix and Python lists/numbers, all would work ok as expected; but now it makes FuncDesigner code to work much slower or unexpectedly or doesn't work at all instead.  
So, does anyone mind if I'll commit some changes to numpy __mul__, __div__ etc?  
I intend to implement the following walkaround:  
Now the code looks like this for array:  
  
    def __mul__(self, i):  
        return asarray(multiply(self, i))  
  
and like this for numpy/matrixlib/defmatrix.py:  
  
    def __mul__(self, other):  
        if isinstance(other,(N.ndarray, list, tuple)) :  
            return N.dot(self, asmatrix(other))  
        if isscalar(other) or not hasattr(other, '__rmul__') :  
            return N.dot(self, other)  
        return NotImplemented  
  
and I want to add an empty class named "CNumpyLeftOperatorOverloaded" to numpy, and if someone defines his class as a child of the one, __mul__ and others will not invoke __div__ etc, calling otherClass.__rdiv__ etc:  
  
    def __mul__(self, i):  
        return asarray(multiply(self, i)) if not isinstance(i,CNumpyLeftOperatorOverloaded) else i.__rmul__(self)  
and declare my class as a child of the one.  
  
As far as I understood, the changes should be added to numpy/core/defcherarray.py  
So, does anyone mind me to implement it?  
D.  
  
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