Calculate pearson correlation coefficient.

  Args:
    predictions: The raw predictions.
    labels: The actual labels.
    weights_fn: Weighting function.

  Returns:
    The pearson correlation coefficient.

def pearson_correlation_coefficient(predictions, labels, weights_fn=None):
  """Calculate pearson correlation coefficient.

  Args:
    predictions: The raw predictions.
    labels: The actual labels.
    weights_fn: Weighting function.

  Returns:
    The pearson correlation coefficient.
  """
  del weights_fn
  _, pearson = tf.contrib.metrics.streaming_pearson_correlation(predictions,
                                                                labels)
  return pearson, tf.constant(1.0)