building_features_in_triage.md

Tips on Feature Creation in Triage

Some example config files with feature definitions

1. medical early warning system
2. donors choose
3. education project
4. hiv retention

Keep in mind that some odf the examples above may use an earlier version of Triage so you may need to tweak the feature configs a little bit.

creating typical categorical features

        categoricals_imputation:
            max:
              type: 'null_category'


            - # sex
                column: sex
                choice_query: select distinct sex from clean.demporaphics
                metrics: 
                  - max 

            - # urban/rural - using  a subset of values manually specified
                column: locality_type
                choices: [urban, rural]
                metrics:
                  - max  


    categoricals:
      - # top 50 diagnosis
        column: 'dx'
        choice_query: |
                SELECT DISTINCT dx
                        FROM (
                                SELECT dx,
                                        count(*)
                                  FROM clean.diagnosis
                                  GROUP BY dx order by count(*) desc limit 50
                            ) AS code_counts

        metrics:
          - 'max'
          - 'count'

Creating "Age" feature

be careful about feature_start_date

  - # demographics
    prefix: 'demos'
    from_obj: |
          (select entity_id, sex,race,birth_date,zip_code,
          greatest(birth_date,'2011-01-01') as dob from clean.demographics) as dems
    knowledge_date_column: 'dob'

    aggregates:
      - # age in years
        quantity:
          age: "extract(year from age('{collate_date}'::date,  birth_date::date))"
        metrics:
          - 'max'

Creating other temporal features

days since last event

- 
  prefix: 'days_since'
  from_obj: "(SELECT * FROM staging.entity_all_events) AS events"
  knowledge_date_column: 'event_date'
  aggregates:
  
    - # days since last event
      quantity:
        last_event: "'{collate_date}'::DATE - event_date"
      metrics: ['min']



    - # days since last event of a certain type
      quantity:
        last_event_of_type_X: case when event_type='X' then ('{collate_date}'::DATE - event_end_date::DATE) end
  metrics:
      metrics: ['min']

  intervals: ['50y']