[Numpy-discussion] possible bug: __array_wrap__ is not called during arithmetic operations in some cases
Eric Firing
efiring@hawaii....
Sun Feb 22 17:21:59 CST 2009
Darren Dale wrote:
> Does anyone know why __array_wrap__ is not called for subclasses during
> arithmetic operations where an iterable like a list or tuple appears to
> the right of the subclass? When I do "mine*[1,2,3]", array_wrap is not
> called and I get an ndarray instead of a MyArray. "[1,2,3]*mine" is
> fine, as is "mine*array([1,2,3])". I see the same issue with division,
The masked array subclass does not show this behavior:
In [3]:np.ma.arange(3) * [1,2,3]
Out[3]:
masked_array(data = [0 2 6],
mask = False,
fill_value = 999999)
In [4]:[1,2,3] * np.ma.arange(3)
Out[4]:
masked_array(data = [0 2 6],
mask = False,
fill_value = 999999)
Eric
> addition, etc. Here is a demonstration, observed with svn 6456:
>
> import numpy as np
>
> class MyArray(np.ndarray):
>
> __array_priority__ = 20
>
> def __new__(cls):
> return np.asarray(1).view(cls).copy()
>
> def __array_wrap__(self, obj, context=None):
> print 'array wrap:', self, obj, context
> return obj.view(type(self))
>
> def __str__(self):
> return 'MyArray(%s)'%super(MyArray,self).__str__()
>
> mine = MyArray()
>
>
> print 3*mine
> print mine*3
> print [1,2,3]*mine
> print mine*[1,2,3]
> print
> print 3/mine
> print mine/3
> print [1,2,3]*mine
> print mine*[1,2,3]
> print
> print 3+mine
> print mine+3
> print [1,2,3]+mine
> print mine+[1,2,3]
> print
> print 3/mine
> print mine/3
> print [1,2,3]/mine
> print mine/[1,2,3]
> print
> print 3**mine
> print mine**3
> print [1,2,3]**mine
> print mine**[1,2,3]
>
>
> ------------------------------------------------------------------------
>
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