numpy-discussion

[Numpy-discussion] Strange error taking log of PyObject array

[Tom D. <tom...@al...>]

The following works on a float array but not an object array.  It
gives a very strange error message.

(Pdb) numpy.log(numpy.array([19155613843.7], dtype=object))
*** AttributeError: 'float' object has no attribute 'log'
(Pdb) numpy.log([19155613843.7])
array([ 23.67586166])

Re: [Numpy-discussion] Strange error taking log of PyObject array

[Travis O. <oli...@ie...>]

Tom Denniston wrote:
> The following works on a float array but not an object array.  It
> gives a very strange error message.
>
> (Pdb) numpy.log(numpy.array([19155613843.7], dtype=object))
> *** AttributeError: 'float' object has no attribute 'log'
>   
This is expected behavior.  For object arrays the ufuncs look to the 
objects themselves for implementation.   In this case.  The ufunc tries 
to call the log method of each entry in the array.  The first entry is a 
float (which as the error shows) does not have a log attribute and so 
you get a failure.

-Travis

Re: [Numpy-discussion] Strange error taking log of PyObject array

[Tim H. <tim...@co...>]

Travis Oliphant wrote:
> Tom Denniston wrote:
>   
>> The following works on a float array but not an object array.  It
>> gives a very strange error message.
>>
>> (Pdb) numpy.log(numpy.array([19155613843.7], dtype=object))
>> *** AttributeError: 'float' object has no attribute 'log'
>>   
>>     
> This is expected behavior.  For object arrays the ufuncs look to the 
> objects themselves for implementation.   In this case.  The ufunc tries 
> to call the log method of each entry in the array.  The first entry is a 
> float (which as the error shows) does not have a log attribute and so 
> you get a failure.
>   
It seems like we could do better than this. Couldn't the ufunc call 
*itself* on on objects in an object array? That is, ufunc(object_array) 
would be more or less equivalent to map(ufunc, object_array)  [mostly 
less, but hopefully you get the idea]. I haven't looked into the gory 
details, and I'm not likely to soon since I'm tied up with other stuff, 
but I figured I'd toss the idea into the ring.

-tim