> ## Documentation Index
> Fetch the complete documentation index at: https://docs.openlayer.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Column contains string

> Learn how to use the column contains string test

## Definition

Let A be a column in a dataset containing **strings**. Let B be a column in a dataset containing **lists of strings**.

The column contains string test asserts that the list of strings in B contains the string in A on a per-row basis.

For example:

| A   | B                | Result   |
| --- | ---------------- | -------- |
| "a" | \["a", "b", "c"] | ✓ Passed |
| "b" | \["a", "b", "c"] | ✓ Passed |
| "c" | \["a", "b", "c"] | ✓ Passed |
| "d" | \["a", "b", "c"] | x Failed |

Since "d" is not in the list \["a", "b", "c"], the test fails.

## Taxonomy

* **Task types**: LLM, tabular classification, tabular regression, text classification.
* **Availability**: <Tooltip tip="Continuously evaluate your models and datasets as you iterate on their versions.">development</Tooltip>
  and <Tooltip tip="Monitor a model in production, measure its health, check for drifts and set up alerts.">monitoring</Tooltip>.

## Why it matters

* In particular for RAG LLM projects, the context retriever will return a list of the top K contexts. The column contains string test can be used to ensure that the context retriever returns at least one of the correct contexts.

## Test configuration examples

If you are writing a `tests.json`, here are a few valid configurations for the character length test:

<CodeGroup>
  ```json Development theme={null}
  [
    {
      "name": "Values in 'top_k_contexts' should be in 'correct_context' for every row",
      "description": "Asserts that the list of strings in 'top_k_contexts' contains the string in 'correct_context' on a per-row basis.",
      "type": "integrity",
      "subtype": "expectColumnAToBeInColumnB",
      "thresholds": [
        {
          "insightName": "expectColumnAToBeInColumnB",
          "insightParameters": [
            {
              "name": "column_a_name",
              "value": "correct_context" // Selects column A (`correct_context`)
            },
            {
              "name": "column_b_name",
              "value": "top_k_contexts" // Selects column B (`top_k_contexts`)
            }
          ],
          "measurement": "failingRowCount",  // Use the absolute row count
          "operator": "<=",
          "value": 0
        }
      ],
      "subpopulationFilters": null,
      "mode": "development",
      "usesValidationDataset": true, // Apply test to the validation set
      "usesTrainingDataset": false,
      "usesMlModel": false,
      "syncId": "b4dee7dc-4f15-48ca-a282-63e2c04e0689" // Some unique id
    },
    {
      "name": "Values in 'top_k_contexts' should be in 'correct_context' for at least 80% of the rows",
      "description": "Asserts that the list of strings in 'top_k_contexts' contains the string in 'correct_context' on a per-row basis.",
      "type": "integrity",
      "subtype": "expectColumnAToBeInColumnB",
      "thresholds": [
        {
          "insightName": "expectColumnAToBeInColumnB",
          "insightParameters": [
            {
              "name": "column_a_name",
              "value": "correct_context" // Selects column A (`correct_context`)
            },
            {
              "name": "column_b_name",
              "value": "top_k_contexts" // Selects column B (`top_k_contexts`)
            }
          ],
          "measurement": "failingRowPercentage", // Use the row percentage
          "operator": "<",
          "value": 0.2
        }
      ],
      "subpopulationFilters": null,
      "mode": "development",
      "usesValidationDataset": true, // Apply test to the validation set
      "usesTrainingDataset": false,
      "usesMlModel": false,
      "syncId": "96622fba-ea00-4e42-8f42-5e8f5f60805f" // Some unique id
    }
  ]
  ```

  ```json Monitoring theme={null}
  [
    {
      "name": "Values in 'top_k_contexts' should be in 'correct_context' for every row",
      "description": "Asserts that the list of strings in 'top_k_contexts' contains the string in 'correct_context' on a per-row basis.",
      "type": "integrity",
      "subtype": "expectColumnAToBeInColumnB",
      "thresholds": [
        {
          "insightName": "expectColumnAToBeInColumnB",
          "insightParameters": [
            {
              "name": "column_a_name",
              "value": "correct_context" // Selects column A (`correct_context`)
            },
            {
              "name": "column_b_name",
              "value": "top_k_contexts" // Selects column B (`top_k_contexts`)
            }
          ],
          "measurement": "failingRowCount", // Use the absolute row count
          "operator": "<=",
          "value": 0
        }
      ],
      "subpopulationFilters": null,
      "mode": "monitoring",
      "usesProductionData": true,
      "evaluationWindow": 3600, // 1 hour
      "delayWindow": 0,
      "syncId": "b4dee7dc-4f15-48ca-a282-63e2c04e0689" // Some unique id
    },
    {
      "name": "Values in 'top_k_contexts' should be in 'correct_context' for at least 80% of the rows",
      "description": "Asserts that the list of strings in 'top_k_contexts' contains the string in 'correct_context' on a per-row basis.",
      "type": "integrity",
      "subtype": "expectColumnAToBeInColumnB",
      "thresholds": [
        {
          "insightName": "expectColumnAToBeInColumnB",
          "insightParameters": [
            {
              "name": "column_a_name",
              "value": "correct_context" // Selects column A (`correct_context`)
            },
            {
              "name": "column_b_name",
              "value": "top_k_contexts" // Selects column B (`top_k_contexts`)
            }
          ],
          "measurement": "failingRowPercentage", // Use the row percentage
          "operator": "<",
          "value": 0.2
        }
      ],
      "subpopulationFilters": null,
      "mode": "monitoring",
      "usesProductionData": true,
      "evaluationWindow": 3600, // 1 hour
      "delayWindow": 0,
      "syncId": "96622fba-ea00-4e42-8f42-5e8f5f60805f" // Some unique id
    }
  ]
  ```
</CodeGroup>

## Related

* [Great Expectations test](/tests/integrity/great-expectations).