import tensorflow as tf
from tensorflow import keras
from tensorflow.keras import backend as K


def loss(a,b,K=K):
    """correlation between a and the first entry of b should be zero. Correlations are hard to optimize. So use corvariance and metric keeping properties"""
    if len(b.shape)>1:
        b=b[:,0]
    if len(a.shape)>1:
        a=a[:,0]

    return K.abs(K.mean((a-K.mean(a))*(b-K.mean(b))))


if __name__=='__main__':
    import numpy as np
    x=np.random.uniform(-1,1,size=(1000,2))
    print(numpyloss2d(x[:,0],x[:,1],n=25))