[Numpy-discussion] Interpolation question

[Andrea Gavana]

On 28 March 2010 08:26, Anne Archibald wrote:
> On 27 March 2010 20:24, Andrea Gavana <andrea.gavana at gmail.com> wrote:
>> Hi All,
>>
>>    I have an interpolation problem and I am having some difficulties
>> in tackling it. I hope I can explain myself clearly enough.
>>
>> Basically, I have a whole bunch of 3D fluid flow simulations (close to
>> 1000), and they are a result of different combinations of parameters.
>> I was planning to use the Radial Basis Functions in scipy, but for the
>> moment let's assume, to simplify things, that I am dealing only with
>> one parameter (x). In 1000 simulations, this parameter x has 1000
>> values, obviously. The problem is, the outcome of every single
>> simulation is a vector of oil production over time (let's say 40
>> values per simulation, one per year), and I would like to be able to
>> interpolate my x parameter (1000 values) against all the simulations
>> (1000x40) and get an approximating function that, given another x
>> parameter (of size 1x1) will give me back an interpolated production
>> profile (of size 1x40).
>
> If I understand your problem correctly, you have a function taking one
> value as input (or one 3D vector) and returning a vector of length 40.
> You want to know whether there are tools in scipy to support this.
>
> I'll say first that it's not strictly necessary for there to be: you
> could always just build 40 different interpolators, one for each
> component of the output. After all, there's no interaction in the
> calculations between the output coordinates. This is of course
> awkward, in that you'd like to just call F(x) and get back a vector of
> length 40, but that can be remedied by writing a short wrapper
> function that simply calls all 40 interpolators.

Thank you Anne and Josef, my explanation was very bad but your
suggestions opened up my mind :-D . I believe I am going to give the
40 interpolators a try, although you mentioned that RBFs are going to
have some problems if the vectors' sizes are too big...

I planned for a multidimensional interpolation of about 10 parameters
(each of these has 1000 elements), but at this point I am afraid it
will not work. If any of you is aware of another methodology/library I
could use (Fortran is also fine, as long as I can wrap it with f2py)
for this problem please feel free to put me on the right track.

Thank you again for your suggestions.

Andrea.

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