# OffsetMappingFilter **`class OffsetMappingFilter(config)`** Bases: [`Filter`](squirro.lib.nlp.steps.filters.Filter.md#squirro.lib.nlp.steps.filters.Filter) **Takes a prediction field of the form:** [ { “start”: int, “end”: int, “label”: str, “text”: str }, … ] and adjusts the start and end offsets according to the mapping Parameters - `entities_field` ([`str`](https://docs.python.org/3.11/library/stdtypes.html#str)) – Field with list of ner entities - `index_mapping_field` ([`str`](https://docs.python.org/3.11/library/stdtypes.html#str)) – Field with mapping information - `output_field` ([`str`](https://docs.python.org/3.11/library/stdtypes.html#str)`, ``'entities'`) – Field to write resulting entities Methods SummaryMethods Documentation **`process_doc(doc)`** Process a document Parameters `doc` ([`Document`](../technical/libnlp/base.md#squirro.lib.nlp.document.Document)) – Document Returns Processed document Return type [Document](../technical/libnlp/base.md#squirro.lib.nlp.document.Document)