sdks/python/apache_beam/examples/inference/gemini_text_classification.py

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""" A sample pipeline using the RunInference API to classify text using an LLM.
This pipeline creates a set of prompts and sends it to a Gemini service then
returns the predictions from the classifier model. This example uses the
gemini-2.0-flash-001 model.
"""

import argparse
import logging
from collections.abc import Iterable

import apache_beam as beam
from apache_beam.ml.inference.base import PredictionResult
from apache_beam.ml.inference.base import RunInference
from apache_beam.ml.inference.gemini_inference import GeminiModelHandler
from apache_beam.ml.inference.gemini_inference import generate_from_string
from apache_beam.options.pipeline_options import PipelineOptions
from apache_beam.options.pipeline_options import SetupOptions
from apache_beam.runners.runner import PipelineResult


def parse_known_args(argv):
  """Parses args for the workflow."""
  parser = argparse.ArgumentParser()
  parser.add_argument(
      '--output',
      dest='output',
      type=str,
      required=True,
      help='Path to save output predictions.')
  parser.add_argument(
      '--api_key',
      dest='api_key',
      type=str,
      required=False,
      help='Gemini Developer API key.')
  parser.add_argument(
      '--cloud_project',
      dest='project',
      type=str,
      required=False,
      help='GCP Project')
  parser.add_argument(
      '--cloud_region',
      dest='location',
      type=str,
      required=False,
      help='GCP location for the Endpoint')
  return parser.parse_known_args(argv)


class PostProcessor(beam.DoFn):
  def process(self, element: PredictionResult) -> Iterable[str]:
    for part in element.inference.parts:
      try:
        output_text = part.text
        yield f"Input: {element.example}, Output: {output_text}"
      except Exception as e:
        print(f"Can't decode inference for element: {element.example}, got {e}")
        raise e


def run(
    argv=None, save_main_session=True, test_pipeline=None) -> PipelineResult:
  """
  Args:
    argv: Command line arguments defined for this example.
    save_main_session: Used for internal testing.
    test_pipeline: Used for internal testing.
  """
  known_args, pipeline_args = parse_known_args(argv)
  pipeline_options = PipelineOptions(pipeline_args)
  pipeline_options.view_as(SetupOptions).save_main_session = save_main_session
  model_handler = GeminiModelHandler(
      model_name='gemini-2.0-flash-001',
      request_fn=generate_from_string,
      api_key=known_args.api_key,
      project=known_args.project,
      location=known_args.location)

  pipeline = test_pipeline
  if not test_pipeline:
    pipeline = beam.Pipeline(options=pipeline_options)

  prompts = [
      "What is 5+2?",
      "Who is the protagonist of Lord of the Rings?",
      "What is the air-speed velocity of a laden swallow?"
  ]

  read_prompts = pipeline | "Get prompt" >> beam.Create(prompts)
  predictions = read_prompts | "RunInference" >> RunInference(model_handler)
  processed = predictions | "PostProcess" >> beam.ParDo(PostProcessor())
  _ = processed | "PrintOutput" >> beam.Map(print)
  _ = processed | "WriteOutput" >> beam.io.WriteToText(
      known_args.output, shard_name_template='', append_trailing_newlines=True)

  result = pipeline.run()
  result.wait_until_finish()
  return result


if __name__ == '__main__':
  logging.getLogger().setLevel(logging.INFO)
  run()