class_docstr: Computes PredictionDifference.
class_docstr_tok: ["Computes","PredictionDifference","."]
code: def extract_output(
      self, accumulator: _SymmetricPredictionDifferenceAccumulator
  ) -> Dict[metric_types.MetricKey, float]:
      return {
          self._key: accumulator.total_pointwise_sym_diff
          / accumulator.num_weighted_examples
      }
  
file_path: model-analysis/tensorflow_model_analysis/metrics/prediction_difference_metrics.py
imports: import dataclasses
  from typing import Optional, Dict, Iterable, List
  import apache_beam
  from tensorflow_model_analysis.metrics import metric_types
  from tensorflow_model_analysis.metrics import metric_util
  from tensorflow_model_analysis.proto import config_pb2
  from tensorflow_model_analysis.utils import model_util
label_desc: Use image node_id 5 for calling the _SymmetricPredictionDifferenceCombiner obj's underlying member method code with example usage: obj.extract_output(accumulator) and returns: dict