Matt Feinstein wrote:
> Is there an optimal way to apply a function to the elements of a two-d
> array?
>
> What I'd like to do is define some function:
>
> def plone(x):
> return x+1
>
> and then apply it elementwise to a 2-D numarray. I intend to treat the
> function as a variable, so ufuncs are probably not appropriate-- I
> realize that what I'm looking for won't be terrifically efficient,
> but I'd like to avoid doing it in the -worst- possible way.
>
> Some things I've looked at include things like
>
> def applyfun(m,f):
> elist = [f(e) for e in m]
> return reshape(elist,m.shape)
>
> however, I can see that this looks neat but probably generates several
> copies of the array, which is not so neat.
>
> Is there a better way?
I must be missing something, because the simplest possible thing seems
to work for me:
py> import numarray as na
py> def plus1(arr):
... return arr + 1
...
py> def apply_func(arr, f):
... return f(arr)
...
py> a = na.arange(20, shape=(4, 5))
py> a
array([[ 0, 1, 2, 3, 4],
[ 5, 6, 7, 8, 9],
[10, 11, 12, 13, 14],
[15, 16, 17, 18, 19]])
py> apply_func(a, plus1)
array([[ 1, 2, 3, 4, 5],
[ 6, 7, 8, 9, 10],
[11, 12, 13, 14, 15],
[16, 17, 18, 19, 20]])
Is this not what you wanted?
STeVe
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