text: import tensorflow as tf
  
  
  def r_squared(y, y_pred):
      """
      :param y: true valuse (tf.Tensor or np.ndarray)
      :param y_pred: predicted values (tf.Tensor or np.ndarray)
      :return:
  
      r2 score metric for tensorflow
      """
      residual = tf.reduce_sum(tf.square(tf.subtract(y, y_pred)))
      total = tf.reduce_sum(tf.square(tf.subtract(y, tf.reduce_mean(y))))
      r2 = tf.subtract(1.0, tf.math.divide(residual, total))
      return r2
  