class_docstr: Combine function that computes metric using initial state from extracts.
docstr: Init.
  
  
  Args:
    computations: List of MetricComputations.
docstr_tok: ["Init",".","Args",":","computations",":","List","of","MetricComputations","."]
code: def __init__(
      self, computations: List[metric_types.MetricComputation]
  ):
      """Init.
  
  
      Args:
        computations: List of MetricComputations.
      """
      super().__init__(*[c.combiner for c in computations])
      self._num_compacts = beam.metrics.Metrics.counter(
          constants.METRICS_NAMESPACE, "num_compacts"
      )
  
imports: import copy
  import datetime
  import itertools
  import numbers
  from typing import Any, Dict, Iterable, Iterator, List, NamedTuple, Optional, Tuple, Type, TypeVar, Union
  import apache_beam
  import numpy
  from tensorflow_model_analysis import constants
  from tensorflow_model_analysis.api import types
  from tensorflow_model_analysis.evaluators import counter_util
  from tensorflow_model_analysis.evaluators import eval_saved_model_util
  from tensorflow_model_analysis.evaluators import evaluator
  from tensorflow_model_analysis.evaluators import jackknife
  from tensorflow_model_analysis.evaluators import keras_util
  from tensorflow_model_analysis.evaluators import metrics_validator
  from tensorflow_model_analysis.evaluators import poisson_bootstrap
  from tensorflow_model_analysis.extractors import slice_key_extractor
  from tensorflow_model_analysis.metrics import metric_specs
  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.slicer import slicer_lib
  from tensorflow_model_analysis.utils import model_util
  from tensorflow_model_analysis.utils import util
  from tensorflow_metadata.proto.v0 import schema_pb2
label_desc: Use image node_id 1 to create a new _ComputationsCombineFn object from inherited base classes: beam.combiners with example: obj = _ComputationsCombineFn(computations)