我想在Keras中使用tensorflow的度量(皮尔逊相关性)

import tensorflow as tf
from keras import backend as K

def pearson_correlation(y_true, y_pred):
    x = y_true - K.mean(y_true)
    y = y_pred - K.mean(y_pred)
    pearson = K.sum(x * y) / (K.sqrt(K.sum(K.square(x))) * K.sqrt(K.sum(K.square(y))))
    return pearson

model.compile(optimizer='adam', loss='mse', metrics=[pearson_correlation])