# ProximityFilter **`class ProximityFilter(config)`** Bases: [`RegexFilter`](squirro.lib.nlp.steps.filters.RegexFilter.md#squirro.lib.nlp.steps.filters.RegexFilter) The proximity [`RegexFilter`](squirro.lib.nlp.steps.filters.RegexFilter.md#squirro.lib.nlp.steps.filters.RegexFilter) filters all `Document` by checking if terms exist within a specified proximity. **Note** - The format for proximity rules is based on the [Squirro Phrase Search syntax](../technical/search/features/query-syntax.md#search-query-syntax) (e.g. `"issue shares~6"`). To make the search one directional append `"|"` (e.g. `"issue shares~6|"`). It is possible to use more than 2 terms where the distance is used between consecutive terms, or use a single exact match term without proximity distance. - Expressions are case-insensitive. - There is a max of 20 words per rule to limit the complexity of the regex **Input** - all input fields needs to be of type [`str`](https://docs.python.org/3.11/library/stdtypes.html#str). **Output** - the output field is filled with data of type [`str`](https://docs.python.org/3.11/library/stdtypes.html#str). Parameters - `type` ([`str`](https://docs.python.org/3.11/library/stdtypes.html#str)) – proximity - `blacklist_terms` ([`list`](https://docs.python.org/3.11/library/stdtypes.html#list)`, ``[``]`) – List of blacklist proximity terms - `whitelist_terms` ([`list`](https://docs.python.org/3.11/library/stdtypes.html#list)`, ``[``]`) – List of whitelist proximity terms **Example** ```json { "step": "filter", "type": "proximity", "fields": ["body"], "matching_label": "m&a", "output_field": "prediction", "whitelist_terms": ["appoint CEO~3"] } ``` Attributes SummaryAttributes Documentation **`REG_FLAGS = 2`**