Support for Extraction Filter

[sid88in]

http://druid.io/docs/latest/querying/filters.html

{ "filter": { "type": "extraction", "dimension": "product", "value": "bar_1", "extractionFn": { "type": "lookup", "lookup": { "type": "map", "map": { "product_1": "bar_1", "product_5": "bar_1", "product_3": "bar_1" } } } } }

[dakra]

Extractions are in pydruid.utils.dimensions. Map lookup extraction in particular is defined here: https://github.com/druid-io/pydruid/blob/master/pydruid/utils/dimensions.py#L123

[magor]

@dakra , could you please elaborate on how to use linked class in filter specification (as in, using pydruid.utils.filters.Filter class)?

This pull request seems related: #76

[dakra]

@magor I was thinking about dimension extractions. You're right that for lookup extraction on the Filter you have to wait for #76