data interpolation

[marco.nawijn at colosso.nl]

On Thursday, November 3, 2016 at 11:08:34 AM UTC+1, Heli wrote:
> Hi, 
> 
> I have a question about data interpolation using python. I have a big ascii file containg data in the following format and around 200M points. 
> 
> id, xcoordinate, ycoordinate, zcoordinate
> 
> then I have a second file containing data in the following format, ( 2M values) 
> 
> id, xcoordinate, ycoordinate, zcoordinate, value1, value2, value3,..., valueN
> 
> I would need to get values for x,y,z coordinates of file 1 from values of file2.  
> 
> I don´t know whether my data in file1 and 2 is from structured or unstructured grid source. I was wondering which interpolation module either from scipy or scikit-learn you recommend me to use?
> 
> I would also appreciate if you could recommend me some sample example/reference. 
> 
> Thanks in Advance for your help,

Take a look at the scipy.spatial.KDTree class:
https://docs.scipy.org/doc/scipy-0.14.0/reference/generated/scipy.spatial.KDTree.html

Given your example, you would build the tree (using the coordinates) 
from the second file. Subsequently, you can use one of the query 
methods for every point in your first file. From this it is up to 
you how to transfer (interpolate) the values.

Marco