b93e7e8843
@ethervoid , looks good! i just rewrote the English a bit. Let me know if this is okay then we can update all the live docs.
366 lines
15 KiB
Markdown
366 lines
15 KiB
Markdown
# Discovery Functions
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If you are using the [discovery methods](https://carto.com/docs/carto-engine/data/overview/#discovery-methods) from the Data Observatory, use the following functions to retrieve [boundary](https://carto.com/docs/carto-engine/data/overview/#boundary-data) and [measures](https://carto.com/docs/carto-engine/data/overview/#measures-data) data.
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## OBS_Search(search_term)
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Use arbitrary text to search all available measures
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#### Arguments
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Name | Description
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--- | ---
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search_term | a string to search for available measures
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boundary_id | a string identifier for a boundary geometry (optional)
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#### Returns
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A TABLE containing the following properties
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Key | Description
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--- | ---
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id | the unique id of the measure for use with the ```OBS_GetMeasure``` function
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name | the human readable name of the measure
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description | a brief description of the measure
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aggregate | **sum** are raw count values, **median** are statistical medians, **average** are statistical averages, **undefined** other (e.g. an index value)
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source | where the data came from (e.g. US Census Bureau)
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#### Example
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```SQL
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SELECT * FROM OBS_Search('home value')
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```
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## OBS_GetAvailableBoundaries(point_geometry)
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Returns available `boundary_id`s at a given point geometry.
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#### Arguments
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Name | Description
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--- | ---
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point_geometry | a WGS84 point geometry (e.g. the_geom)
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#### Returns
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A TABLE containing the following properties
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Key | Description
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--- | ---
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boundary_id | a boundary identifier from the [Boundary ID Glossary](https://carto.com/docs/carto-engine/data/glossary/#boundary-ids)
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description | a brief description of the boundary dataset
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time_span | the timespan attached the boundary. this does not mean that the boundary is invalid outside of the timespan, but is the explicit timespan published with the geometry.
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#### Example
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```SQL
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SELECT * FROM OBS_GetAvailableBoundaries(CDB_LatLng(40.7, -73.9))
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```
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## OBS_GetAvailableNumerators(bounds, filter_tags, denom_id, geom_id, timespan)
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Return available numerators within a boundary and with the specified
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`filter_tags`.
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#### Arguments
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Name | Type | Description
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--- | --- | ---
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bounds | Geometry(Geometry, 4326) | a geometry which some of the numerator's data must intersect with
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filter_tags | Text[] | a list of filters. Only numerators for which all of these apply are returned `NULL` to ignore (optional)
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denom_id | Text | the ID of a denominator to check whether the numerator is valid against. Will not reduce length of returned table, but will change values for `valid_denom` (optional)
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geom_id | Text | the ID of a geometry to check whether the numerator is valid against. Will not reduce length of returned table, but will change values for `valid_geom` (optional)
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timespan | Text | the ID of a timespan to check whether the numerator is valid against. Will not reduce length of returned table, but will change values for `valid_timespan` (optional)
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#### Returns
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A TABLE containing the following properties
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Key | Type | Description
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--- | ---- | -----------
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numer_id | Text | The ID of the numerator
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numer_name | Text | A human readable name for the numerator
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numer_description | Text | Description of the numerator. Is sometimes NULL
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numer_weight | Numeric | Numeric "weight" of the numerator. Ignored.
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numer_license | Text | ID of the license for the numerator
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numer_source | Text | ID of the source for the numerator
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numer_type | Text | Postgres type of the numerator
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numer_aggregate | Text | Aggregate type of the numerator. If `'SUM'`, this can be normalized by area
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numer_extra | JSONB | Extra information about the numerator column. Ignored.
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numer_tags | Text[] | Array of all tags applying to this numerator
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valid_denom | Boolean | True if the `denom_id` argument is a valid denominator for this numerator, False otherwise
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valid_geom | Boolean | True if the `geom_id` argument is a valid geometry for this numerator, False otherwise
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valid_timespan | Boolean | True if the `timespan` argument is a valid timespan for this numerator, False otherwise
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#### Examples
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Obtain all numerators that are available within a small rectangle.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableNumerators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326))
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```
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Obtain all numerators that are available within a small rectangle and are for
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the United States only.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableNumerators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), '{section/tags.united_states}');
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```
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Obtain all numerators that are available within a small rectangle and are
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employment related for the United States only.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableNumerators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), '{section/tags.united_states, subsection/tags.employment}');
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```
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Obtain all numerators that are available within a small rectangle and are
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related to both employment and age & gender for the United States only.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableNumerators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), '{section/tags.united_states, subsection/tags.employment, subsection/tags.age_gender}');
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```
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Obtain all numerators that work with US population (`us.census.acs.B01003001`)
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as a denominator.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableNumerators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, 'us.census.acs.B01003001')
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WHERE valid_denom IS True;
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```
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Obtain all numerators that work with US states (`us.census.tiger.state`)
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as a geometry.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableNumerators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, NULL, 'us.census.tiger.state')
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WHERE valid_geom IS True;
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```
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Obtain all numerators available in the timespan `2011 - 2015`.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableNumerators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, NULL, NULL, '2011 - 2015')
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WHERE valid_timespan IS True;
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```
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## OBS_GetAvailableDenominators(bounds, filter_tags, numer_id, geom_id, timespan)
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Return available denominators within a boundary and with the specified
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`filter_tags`.
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#### Arguments
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Name | Type | Description
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--- | --- | ---
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bounds | Geometry(Geometry, 4326) | a geometry which some of the denominator's data must intersect with
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filter_tags | Text[] | a list of filters. Only denominators for which all of these apply are returned `NULL` to ignore (optional)
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numer_id | Text | the ID of a numerator to check whether the denominator is valid against. Will not reduce length of returned table, but will change values for `valid_numer` (optional)
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geom_id | Text | the ID of a geometry to check whether the denominator is valid against. Will not reduce length of returned table, but will change values for `valid_geom` (optional)
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timespan | Text | the ID of a timespan to check whether the denominator is valid against. Will not reduce length of returned table, but will change values for `valid_timespan` (optional)
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#### Returns
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A TABLE containing the following properties
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Key | Type | Description
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--- | ---- | -----------
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denom_id | Text | The ID of the denominator
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denom_name | Text | A human readable name for the denominator
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denom_description | Text | Description of the denominator. Is sometimes NULL
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denom_weight | Numeric | Numeric "weight" of the denominator. Ignored.
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denom_license | Text | ID of the license for the denominator
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denom_source | Text | ID of the source for the denominator
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denom_type | Text | Postgres type of the denominator
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denom_aggregate | Text | Aggregate type of the denominator. If `'SUM'`, this can be normalized by area
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denom_extra | JSONB | Extra information about the denominator column. Ignored.
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denom_tags | Text[] | Array of all tags applying to this denominator
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valid_numer | Boolean | True if the `numer_id` argument is a valid numerator for this denominator, False otherwise
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valid_geom | Boolean | True if the `geom_id` argument is a valid geometry for this denominator, False otherwise
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valid_timespan | Boolean | True if the `timespan` argument is a valid timespan for this denominator, False otherwise
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#### Examples
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Obtain all denominators that are available within a small rectangle.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableDenominators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326));
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```
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Obtain all denominators that are available within a small rectangle and are for
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the United States only.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableDenominators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), '{section/tags.united_states}');
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```
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Obtain all denominators for male population (`us.census.acs.B01001002`).
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableDenominators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, 'us.census.acs.B01001002')
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WHERE valid_numer IS True;
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```
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Obtain all denominators that work with US states (`us.census.tiger.state`)
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as a geometry.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableDenominators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, NULL, 'us.census.tiger.state')
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WHERE valid_geom IS True;
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```
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Obtain all denominators available in the timespan `2011 - 2015`.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableDenominators(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, NULL, NULL, '2011 - 2015')
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WHERE valid_timespan IS True;
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```
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## OBS_GetAvailableGeometries(bounds, filter_tags, numer_id, denom_id, timespan, number_geometries)
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Return available geometries within a boundary and with the specified
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`filter_tags`.
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#### Arguments
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Name | Type | Description
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--- | --- | ---
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bounds | Geometry(Geometry, 4326) | a geometry which must intersect the geometry
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filter_tags | Text[] | a list of filters. Only geometries for which all of these apply are returned `NULL` to ignore (optional)
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numer_id | Text | the ID of a numerator to check whether the geometry is valid against. Will not reduce length of returned table, but will change values for `valid_numer` (optional)
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denom_id | Text | the ID of a denominator to check whether the geometry is valid against. Will not reduce length of returned table, but will change values for `valid_denom` (optional)
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timespan | Text | the ID of a timespan to check whether the geometry is valid against. Will not reduce length of returned table, but will change values for `valid_timespan` (optional)
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number_geometries | Integer | calculates the score value based on a specified numeric parameter. This is useful if you need to adjust the accuracy of the number of geometries relative to the bounding box. (optional)
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#### Returns
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A TABLE containing the following properties
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Key | Type | Description
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--- | ---- | -----------
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geom_id | Text | The ID of the geometry
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geom_name | Text | A human readable name for the geometry
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geom_description | Text | Description of the geometry. Is sometimes NULL
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geom_weight | Numeric | Numeric "weight" of the geometry. Ignored.
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geom_aggregate | Text | Aggregate type of the geometry. Ignored.
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geom_license | Text | ID of the license for the geometry
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geom_source | Text | ID of the source for the geometry
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geom_type | Text | Postgres type of the geometry
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geom_extra | JSONB | Extra information about the geometry column. Ignored.
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geom_tags | Text[] | Array of all tags applying to this geometry
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valid_numer | Boolean | True if the `numer_id` argument is a valid numerator for this geometry, False otherwise
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valid_denom | Boolean | True if the `geom_id` argument is a valid geometry for this geometry, False otherwise
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valid_timespan | Boolean | True if the `timespan` argument is a valid timespan for this geometry, False otherwise
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score | Numeric | Score between 0 and 100 for this geometry, higher numbers mean that this geometry is a better choice for the passed extent
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numtiles | Numeric | How many raster tiles were read for score, numgeoms, and percentfill estimates
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numgeoms | Numeric | About how many of these geometries fit inside the passed extent
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percentfill | Numeric | About what percentage of the passed extent is filled with these geometries
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estnumgeoms | Numeric | Ignored
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meanmediansize | Numeric | Ignored
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#### Examples
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Obtain all geometries that are available within a small rectangle.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableGeometries(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326));
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```
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Obtain all geometries that are available within a small rectangle and are for
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the United States only.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableGeometries(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), '{section/tags.united_states}');
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```
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Obtain all geometries that work with total population (`us.census.acs.B01003001`).
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableGeometries(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, 'us.census.acs.B01003001')
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WHERE valid_numer IS True;
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```
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Obtain all geometries with timespan `2015`.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableGeometries(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, NULL, NULL, '2015')
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WHERE valid_timespan IS True;
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```
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## OBS_GetAvailableTimespans(bounds, filter_tags, numer_id, denom_id, geom_id)
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Return available timespans within a boundary and with the specified
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`filter_tags`.
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#### Arguments
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Name | Type | Description
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--- | --- | ---
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bounds | Geometry(Geometry, 4326) | a geometry which some of the timespan's data must intersect with
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filter_tags | Text[] | a list of filters. Ignore
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numer_id | Text | the ID of a numerator to check whether the timespans is valid against. Will not reduce length of returned table, but will change values for `valid_numer` (optional)
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denom_id | Text | the ID of a denominator to check whether the timespans is valid against. Will not reduce length of returned table, but will change values for `valid_denom` (optional)
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geom_id | Text | the ID of a geometry to check whether the timespans is valid against. Will not reduce length of returned table, but will change values for `valid_geom` (optional)
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#### Returns
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A TABLE containing the following properties
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Key | Type | Description
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--- | ---- | -----------
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timespan_id | Text | The ID of the timespan
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timespan_name | Text | A human readable name for the timespan
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timespan_description | Text | Ignored
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timespan_weight | Numeric | Ignored
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timespan_aggregate | Text | Ignored
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timespan_license | Text | Ignored
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timespan_source | Text | Ignored
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timespan_type | Text | Ignored
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timespan_extra | JSONB | Ignored
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timespan_tags | JSONB | Ignored
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valid_numer | Boolean | True if the `numer_id` argument is a valid numerator for this timespan, False otherwise
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valid_denom | Boolean | True if the `timespan` argument is a valid timespan for this timespan, False otherwise
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valid_geom | Boolean | True if the `geom_id` argument is a valid geometry for this timespan, False otherwise
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#### Examples
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Obtain all timespans that are available within a small rectangle.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableTimespans(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326));
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```
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Obtain all timespans for total population (`us.census.acs.B01003001`).
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableTimespans(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, 'us.census.acs.B01003001')
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WHERE valid_numer IS True;
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```
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Obtain all timespans that work with US states (`us.census.tiger.state`)
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as a geometry.
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```SQL
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SELECT * FROM cdb_observatory.OBS_GetAvailableTimespans(
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ST_MakeEnvelope(-74, 41, -73, 40, 4326), NULL, NULL, NULL, 'us.census.tiger.state')
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WHERE valid_geom IS True;
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```
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