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Filter Operation

The Filter operation in DocETL is used to selectively process data items based on specific conditions. It behaves similarly to the Map operation, but with a key difference: items that evaluate to false are filtered out of the dataset, allowing you to include or exclude data points from further processing in your pipeline.

Motivation

Filtering is crucial when you need to:

  • Focus on the most relevant data points
  • Remove noise or irrelevant information from your dataset
  • Create subsets of data for specialized analysis
  • Optimize downstream processing by reducing data volume

🚀 Example: Filtering High-Impact News Articles

Let's look at a practical example of using the Filter operation to identify high-impact news articles based on certain criteria.

- name: filter_high_impact_articles
  type: filter
  prompt: |
    Analyze the following news article:
    Title: "{{ input.title }}"
    Content: "{{ input.content }}"

    Determine if this article is high-impact based on the following criteria:
    1. Covers a significant global or national event
    2. Has potential long-term consequences
    3. Affects a large number of people
    4. Is from a reputable source

    Respond with 'true' if the article meets at least 3 of these criteria, otherwise respond with 'false'.

  output:
    schema:
      is_high_impact: boolean

  model: gpt-4-turbo
  validate:
    - isinstance(output["is_high_impact"], bool)

This Filter operation processes news articles and determines whether they are "high-impact" based on specific criteria. Unlike a Map operation, which would process all articles and add an "is_high_impact" field to each, this Filter operation will only pass through articles that meet the criteria, effectively removing low-impact articles from the dataset.

Sample Input and Output

Input: 

[
  {
    "title": "Global Climate Summit Reaches Landmark Agreement",
    "content": "In a historic move, world leaders at the Global Climate Summit have unanimously agreed to reduce carbon emissions by 50% by 2030. This unprecedented agreement involves all major economies and sets binding targets for renewable energy adoption, reforestation, and industrial emissions reduction. Experts hail this as a turning point in the fight against climate change, with potential far-reaching effects on global economies, energy systems, and everyday life for billions of people."
  },
  {
    "title": "Local Bakery Wins Best Croissant Award",
    "content": "Downtown's favorite bakery, 'The Crusty Loaf', has been awarded the title of 'Best Croissant' in the annual City Food Festival. Owner Maria Garcia attributes the win to their use of imported French butter and a secret family recipe. Local food critics praise the bakery's commitment to traditional baking methods."
  }
]

Output: 

[
  {
    "title": "Global Climate Summit Reaches Landmark Agreement",
    "content": "In a historic move, world leaders at the Global Climate Summit have unanimously agreed to reduce carbon emissions by 50% by 2030. This unprecedented agreement involves all major economies and sets binding targets for renewable energy adoption, reforestation, and industrial emissions reduction. Experts hail this as a turning point in the fight against climate change, with potential far-reaching effects on global economies, energy systems, and everyday life for billions of people."
  }
]

This example demonstrates how the Filter operation distinguishes between high-impact news articles and those of more local or limited significance. The climate summit article is retained in the dataset due to its global significance, long-term consequences, and wide-ranging effects. The local bakery story, while interesting, doesn't meet the criteria for a high-impact article and is filtered out of the dataset.

Configuration

Required Parameters

  • name: A unique name for the operation.
  • type: Must be set to "filter".
  • prompt: The prompt template to use for the filtering condition. Access input variables with input.keyname.
  • output: Schema definition for the output from the LLM. It must include only one field, a boolean field.

Optional Parameters

See map optional parameters for additional configuration options, including batch_prompt and max_batch_size.

Validation

For more details on validation techniques and implementation, see operators.

Best Practices

  1. Clear Criteria: Define clear and specific criteria for filtering in your prompt.
  2. Boolean Output: Ensure your prompt guides the LLM to produce a clear boolean output.
  3. Data Flow Awareness: Remember that unlike Map, Filter will reduce the size of your dataset. Ensure this aligns with your pipeline's objectives.