u

from .nearly_even_split import nearly_even_split

from .geometry import ElipsoidTriangulation 

from .template_subs import discoverKeys, templateFiller

from .periodic_stats import periodic_stats

#from import .grep

#import .intervalls

""" periodic stats is a collection of tools for statistics over periodic quantities """

import numpy as np

def periodic_stats(alpha,deg=False) :

    """ statistics of a periodic alpha (radiants)

    If alpha is a vector of angles (radiants) find the average number and the std deviation avoiding the problem of the switch between -180,180 or 360 and 0

    example: alpha=np.array([-180,180]) 

    """

    u=np.cos(alpha)

    v=np.sin(alpha)

    #

    rr=np.array([np.nanmean(u),np.nanmean(v)])

    rr=rr/rr.dot(rr)**0.5

    #

    up=rr[0]*u+rr[1]*v ;

    vp=-rr[1]*u+rr[0]*v

    #

    ap=np.rad2deg(np.arctan2(vp,up).std())

    #

    return np.arctan2(rr[1],rr[0]), np.nanvar(np.arctan2(vp,up))**0.5

if __name__=='__main__' :

   alpha_deg=np.arange(350,371)

   print(np.deg2rad(alpha-360).mean(),np.deg2rad(alpha-360).std())

   print(periodic_stats(np.deg2rad(alpha)))