From: Anne Archibald <peridot.face...@gmail.com>
On 6 April 2010 15:42, Ken Basye <kbas...@jhu.edu> wrote:
> Folks, > I hope this is a simple question. When I created a ufunc with > np.frompyfunc(), I got an error when I called the result with an 'out' > argument:
In fact, ordinary ufuncs do not accept names for their arguments. This is annoying, but fixing it involves rooting around in the bowels of the ufunc machinery, which are not hacker-friendly. Anne
> >>> def foo(x): return x * x + 1 > >>> ufoo = np.frompyfunc(foo, 1, 1) > >>> arr = np.arange(9).reshape(3,3) > >>> ufoo(arr, out=arr) > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > TypeError: 'out' is an invalid keyword to foo (vectorized) > > But I notice that if I just put the array there as a second argument, it > seems to work: > >>> ufoo(arr, arr) > array([[2, 5, 26], > [101, 290, 677], > [1370, 2501, 4226]], dtype=object) > > # and now arr is the same as the return value > > > Is it reasonable to conclude that there is an out-arg in the resulting > ufunc and I just don't know the right name for it? I also tried putting > some other right-shaped array as a second argument and it did indeed get > filled in. > > Thanks as always, > Ken
Thanks - I hadn't noticed that it's apparently only the array methods that can take keyword arguments. So I assume that if I call a '1-arg' ufunc (whether from frompyfunc or an already existing one) with a second argument, the second argument will be used as the output location.
Ken
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