[Numpy-discussion] index method for array objects?
Todd Miller
jmiller at stsci.edu
Thu Jul 25 10:15:03 CDT 2002
Aureli Soria Frisch wrote:
> Hi all,
>
> Has someone implemented a function for arrays that behaves like the
> index(*) method for lists (it should then consider something like a
> tolerance parameter).
>
> I suppose it could be maybe done with array.tolist() and list.index(),
> but have someone implemented something more elegant/array-based?
>
> Thanks in advance
>
> Aureli
>
> PD: (*) index receive a value as an argument and retunrs the index of
> the list member equal to this value...
I think the basics of what you're looking for are something like:
def index(a, b, eps):
return nonzero(abs(a-b) < eps)
which should return all indices at which the absolute value of the
difference between elements of a and b differ by less than eps. e.g.:
>>> import Numeric
>>> index(Numeric.arange(10,20), 15, 1e-5)
array([5])
Todd
--
Todd Miller jmiller at stsci.edu
STSCI / SSG (410) 338 4576
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