[[painless-similarity-context]]
=== Similarity context

Use a Painless script to create a
{es_version}/index-modules-similarity.html[similarity] equation for scoring
documents in a query.

*Variables*

`params` (`Map`, read-only)::
        User-defined parameters passed in as part of the query.

*Variables*

`params` (`Map`, read-only)::
        User-defined parameters passed in at query-time.

`query.boost` (`float`, read-only)::
        The boost value if provided by the query.  If this is not provided the
        value is `1.0f`.

`field.docCount` (`long`, read-only)::
        The number of documents that have a value for the current field.

`field.sumDocFreq` (`long`, read-only)::
        The sum of all terms that exist for the current field.  If this is not
        available the value is `-1`.

`field.sumTotalTermFreq` (`long`, read-only)::
        The sum of occurrences in the index for all the terms that exist in the
        current field.  If this is not available the value is `-1`.

`term.docFreq` (`long`, read-only)::
        The number of documents that contain the current term in the index.

`term.totalTermFreq` (`long`, read-only)::
        The total occurrences of the current term in the index.

`doc.length` (`long`, read-only)::
        The number of tokens the current document has in the current field.

`doc.freq` (`long`, read-only)::
        The number of occurrences of the current term in the current
        document for the current field.

*Return*

`double`::
        The similarity score for the current document.

*API*

The standard <<painless-api-reference, Painless API>> is available.