[Numpy-discussion] Find n closest values

[Nicolas P. Rougier]

Thanks for the answer. 
I was secretly hoping for some kind of hardly-known numpy function that would make things faster auto-magically...


Nicolas


On 22 Jun 2014, at 10:30, Eelco Hoogendoorn <hoogendoorn.eelco at gmail.com> wrote:

> Perhaps you could simplify some statements, but at least the algorithmic complexity is fine, and everything is vectorized, so I doubt you will get huge gains.
> 
> You could take a look at the functions in scipy.spatial, and see how they perform for your problem parameters.
> 
> 
> On Sun, Jun 22, 2014 at 10:22 AM, Nicolas P. Rougier <Nicolas.Rougier at inria.fr> wrote:
> 
> 
> Hi,
> 
> I have an array L with regular spaced values between 0 and width.
> I have a (sorted) array I with irregular spaced values between 0 and width.
> 
> I would like to find the closest value in I for any value in L.
> 
> Currently, I'm using the following script but I wonder if I missed an obvious (and faster) solution:
> 
> 
> import numpy as np
> 
> def find_closest(A, target):
>     idx = A.searchsorted(target)
>     idx = np.clip(idx, 1, len(A) - 1)
>     left = A[idx - 1]
>     right = A[idx]
>     idx -= target - left < right - target
>     return idx
> 
> n, width = 256, 100.0
> 
> # 10 random sorted values in [0,width]
> I = np.sort(np.random.randint(0,width,10))
> 
> # n regular spaced values in [0,width]
> L = np.linspace(0, width, n)
> 
> print I[find_closest(I,L)]
> 
> 
> 
> Nicolas
> _______________________________________________
> NumPy-Discussion mailing list
> NumPy-Discussion at scipy.org
> http://mail.scipy.org/mailman/listinfo/numpy-discussion
> 
> _______________________________________________
> NumPy-Discussion mailing list
> NumPy-Discussion at scipy.org
> http://mail.scipy.org/mailman/listinfo/numpy-discussion