Change the formula of dtw_std

[Seyed Hossein Chavoshi]

Dear All,

I am very new in python programming and I am trying to use the DTW package inside the mlpy in my research. To do so, I need to change the formula of  Euclidean distance in dist_only to another function. Since I am working with the angular sequences the normal Euclidean distance does not work for me. Instead I want to change that function to dist=(1-cos(x-y))/2.

Could you please help me in this issue? I do not even know where I can find that defined function.

I am looking forward to your clues.

With best regards

Hossein

 

[Emil Kjer]

If you are using the DTW package change euclidian distance equation in method "e_dist" in the file mlpy/dtw/cdtw.c:

// euclidean distance

double e_dist(double x, double y)

{

  return fabs(x - y);

}

to

// euclidean distance

double e_dist(double x, double y)

{

  return (1-cos(x-y))/2;

}

And rebuild the package. Haven't tested but it should work. However, the above is the easy solution and you should maybe consider adding an additional distance method used in the std method. 

Let me know if further assistance is needed.

/Emil Kjer