boundary methods update
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andrewxhill
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# Boundaries Functions
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If you are using the [boundary methods](/cartodb-platform/dataobservatory/overview/#boundary-methods) from the Data Observatory, use the following functions to retrieve [Boundary](/cartodb-platform/dataobservatory/overview/#boundary-data) data. You can get global boundary geometries by point or polygon geometries.
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Use the following functions to retrieve [Boundary](/cartodb-platform/dataobservatory/overview/#boundary-data) data. Data ranges from small areas (e.g. US Census Block Groups) to large areas (e.g. Countries). You can access boundaries by point location lookup, bounding box lookup, direct ID access and several other methods described below.
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## OBS_GetGeometry(point_geometry, boundary_id)
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## OBS_GetBoundariesByGeometry(polygon geometry, geometry_id text)
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The ```OBS_GetGeometry(point_geometry, boundary_id)``` function returns a boundary geometry defined as overlapping the point geometry and from the desired boundary set (e.g. Census Tracts). See the [Boundary ID glossary](/cartodb-platform/dataobservatory/glossary/#boundary-ids). This is useful for performing aggregations of points.
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The ```OBS_GetBoundariesByGeometry(geometry, geometry_id)``` method returns a set of boundary geometries that intersect a supplied geometry. This can be used to find all boundaries that are within or overlap a bounding box. You have the ability to choose whether to retrieve all boundaries that intersect your supplied bounding box or only those that fall entirely inside of your bounding box.
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#### Arguments
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Name |Description
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--- | ---
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polygon | a bounding box or other WGS84 geometry
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geometry_id | a string identifier for a boundary geometry
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timespan (optional) | year(s) to request from ('NULL' (default) gives most recent)
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overlap_type (optional) | one of '[intersects](http://postgis.net/docs/manual-2.2/ST_Intersects.html)' (default), '[contains](http://postgis.net/docs/manual-2.2/ST_Contains.html)', or '[within](http://postgis.net/docs/manual-2.2/ST_Within.html)'.
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#### Returns
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A table with the following columns:
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Column Name | Description
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--- | ---
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the_geom | a boundary geometry (e.g., US Census tracts)
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geom_ref | a string identifier for the geometry (e.g., the geoid of a US Census tract)
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#### Example
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Get all Census Tracts in Lower Manhattan plus nearby areas within the supplied bounding box.
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```sql
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SELECT *
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FROM OBS_GetBoundariesByGeometry(
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ST_MakeEnvelope(-74.0251922607,40.6945658517,
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-73.9651107788,40.7377626342,
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4326),
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'us.census.tiger.census_tract')
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```
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#### API Example
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Retrieve all Census tracts contained in a bounding box around Denver, CO as a JSON response:
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```text
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http://observatory.cartodb.com/api/v2/sql?q=SELECT * FROM OBS_GetBoundariesByGeometry(ST_MakeEnvelope(-105.4287704158,39.4600507935,-104.5089737248,40.0901569675,4326),'us.census.tiger.census_tract', NULL, 'contains')
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```
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## OBS_GetPointsByGeometry(polygon geometry, geometry_id text)
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The ```OBS_GetPointsByGeometry(polygon, geometry_id)``` method returns point geometries and their geographical identifiers that intersect (or are contained by) a bounding box polygon and lie on the surface of a boundary corresponding to the boundary with same geographical identifiers (e.g., a point that is on a census tract with the same geoid). This is a useful alternative to ```OBS_GetBoundariesByGeometry``` listed above because it returns much less data for each location.
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#### Arguments
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Name |Description
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--- | ---
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polygon | a bounding box or other geometry
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geometry_id | a string identifier for a boundary geometry
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timespan (optional) | year(s) to request from (`NULL` (default) gives most recent)
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overlap_type (optional) | one of '[intersects](http://postgis.net/docs/manual-2.2/ST_Intersects.html)' (default), '[contains](http://postgis.net/docs/manual-2.2/ST_Contains.html)', or '[within](http://postgis.net/docs/manual-2.2/ST_Within.html)'.
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#### Returns
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A table with the following columns:
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Column Name | Description
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--- | ---
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the_geom | a point geometry on a boundary (e.g., a point that lies on a US Census tract)
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geom_ref | a string identifier for the geometry (e.g., the geoid of a US Census tract)
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#### Example
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Get all Census Tracts in Lower Manhattan plus nearby areas within the supplied bounding box.
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```sql
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SELECT *
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FROM OBS_GetPointsByGeometry(
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ST_MakeEnvelope(-74.0251922607,40.6945658517,
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-73.9651107788,40.7377626342,
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4326),
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'us.census.tiger.census_tract')
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```
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#### API Example
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Retrieve all Census tracts intersecting a bounding box around Denver, CO as a JSON response:
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```text
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http://observatory.cartodb.com/api/v2/sql?q=SELECT * FROM OBS_GetPointsByGeometry(ST_MakeEnvelope(-105.4287704158,39.4600507935,-104.5089737248,40.0901569675,4326), 'us.census.tiger.census_tract', NULL ,'contains')
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```
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## OBS_GetBoundary(point geometry, boundary_id text)
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The ```OBS_GetBoundary(point, boundary_id)``` method returns a boundary geometry defined as overlapping the point geometry and from the desired boundary set (e.g. Census Tracts). See the [Boundary ID glossary table below](below).
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#### Arguments
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Name | Description
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--- | ---
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point_geometry | a WGS84 polygon geometry (the_geom)
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boundary_id | a boundary identifier from the [Boundary ID glossary](/cartodb-platform/dataobservatory/glossary/#boundary-ids)
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boundary_id | a boundary identifier from the [Boundary ID glossary table below](below)
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timespan (optional) | year(s) to request from (`NULL` (default) gives most recent)
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#### Returns
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@ -24,23 +111,25 @@ geom | WKB geometry
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Overwrite a point geometry with a boundary geometry that contains it in your table
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```SQL
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UPDATE tablename SET the_geom = OBS_GetGeometry(the_geom, ' "us.census.tiger".block_group')
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UPDATE tablename
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SET the_geom = OBS_GetBoundary(the_geom, 'us.census.tiger.block_group')
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```
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<!--
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Should add the SQL API call here too
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-->
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## OBS_GetGeometryId(point_geometry, boundary_id)
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## OBS_GetBoundaryId(point geometry, boundary_id text)
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The ```OBS_GetGeometryId(point_geometry, boundary_id)``` returns a unique geometry_id for the boundary geometry that contains a given point geometry. See the [Boundary ID glossary](/cartodb-platform/dataobservatory/glossary/#boundary-ids). The function can be combined with ```OBS_GetGeometryById(geometry_id)``` to create a point aggregation workflow.
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The ```OBS_GetBoundaryId(point, boundary_id)``` returns a unique geometry_id for the boundary geometry that contains a given point geometry. See the [Boundary ID glossary table below](below). The method can be combined with ```OBS_GetBoundaryById(geometry_id)``` to create a point aggregation workflow.
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#### Arguments
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Name |Description
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--- | ---
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point_geometry | a WGS84 polygon geometry (the_geom)
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boundary_id | a boundary identifier from the [Boundary ID glossary](/cartodb-platform/dataobservatory/glossary/#boundary-ids)
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point | a WGS84 point geometry (the_geom)
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boundary_id | a boundary identifier from the [Boundary ID glossary table below](below)
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timespan (optional) | year(s) to request from (`NULL` (default) gives most recent)
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#### Returns
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@ -53,18 +142,21 @@ geometry_id | a string identifier of a geometry in the Boundaries
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Write the geometry_id that contains the point geometry for every row as a new column in your table
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```SQL
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UPDATE tablename SET new_column_name = OBS_GetGeometryId(the_geom, ' "us.census.tiger".block_group')
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UPDATE tablename
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SET new_column_name = OBS_GetBoundaryId(the_geom, ' "us.census.tiger".block_group')
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```
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## OBS_GetGeometryById(geometry_id)
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## OBS_GetBoundaryById(geometry_id text, boundary_id text)
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The ```OBS_GetGeometryById(geometry_id)``` returns the boundary geometry for a unique geometry_id. A geometry_id can be found using the ```OBS_GetGeometryId(point_geometry, boundary_id)``` function described above.
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The ```OBS_GetBoundaryById(geometry_id, boundary_id)``` returns the boundary geometry for a unique geometry_id. A geometry_id can be found using the ```OBS_GetBoundaryId(point, boundary_id)``` method described above.
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#### Arguments
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Name |Description
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Name | Description
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--- | ---
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geometry_id | a string identifier for a Boundary geometry
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boundary_id | a boundary identifier from the [Boundary ID glossary table below](below)
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timespan (optional) | year(s) to request from (`NULL` (default) gives most recent)
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#### Returns
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@ -76,8 +168,80 @@ geom | a WGS84 polygon geometry
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#### Example
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Use a table of geometry_id to select the unique boundaries. Useful with the ```Table from query``` option in CartoDB.
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Use a table of geometry_id to select the unique boundaries. Useful with the ```Create Dataset from Query``` option in CartoDB.
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```SQL
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SELECT OBS_GetGeometryById(geometry_id) the_geom, geometry_id FROM tablename GROUP BY geometry_id
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SELECT OBS_GetBoundaryById(geometry_id) As the_geom, geometry_id
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FROM tablename
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GROUP BY geometry_id
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```
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## OBS_GetBoundariesByPointAndRadius(point geometry, radius numeric, boundary_id text)
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The ```OBS_GetBoundariesByPointAndRadius(point, radius, boundary_id)``` method returns boundary geometries and their geographical identifiers that intersect (or are contained by) a circle centered on a point with a radius.
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#### Arguments
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Name |Description
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--- | ---
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point | a WGS84 point geometry
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radius | a radius (in meters) from the center point
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geometry_id | a string identifier for a boundary geometry
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timespan (optional) | year(s) to request from (`NULL` (default) gives most recent)
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overlap_type (optional) | one of '[intersects](http://postgis.net/docs/manual-2.2/ST_Intersects.html)' (default), '[contains](http://postgis.net/docs/manual-2.2/ST_Contains.html)', or '[within](http://postgis.net/docs/manual-2.2/ST_Within.html)'.
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#### Returns
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A table with the following columns:
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Column Name | Description
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--- | ---
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the_geom | a boundary geometry (e.g., a US Census tract)
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geom_ref | a string identifier for the geometry (e.g., the geoid of a US Census tract)
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#### Example
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Get Census tracts which intersect within 10 miles of Downtown, Colorado. In the Editor, you can simple use "Table from Query" to turn the result into a new dataset.
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```sql
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SELECT *
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FROM OBS_GetBoundariesByPointAndRadius(
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CDB_LatLng(39.7392, -104.9903), -- Denver, Colorado
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10000 * 1.609, -- 10 miles (10km * conversion to miles)
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'us.census.tiger.census_tract')
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```
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## OBS_GetPointsByPointAndRadius(point geometry, radius numeric, boundary_id text)
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The ```OBS_GetPointsByPointAndRadius(point, radius, boundary_id)``` method returns point geometries on boundaries (e.g., a point that lies on a Census tract) and their geographical identifiers that intersect (or are contained by) a circle centered on a point with a radius.
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#### Arguments
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Name |Description
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--- | ---
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point | a WGS84 point geometry
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radius | radius (in meters)
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geometry_id | a string identifier for a boundary geometry
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timespan (optional) | year(s) to request from (`NULL` (default) gives most recent)
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overlap_type (optional) | one of '[intersects](http://postgis.net/docs/manual-2.2/ST_Intersects.html)' (default), '[contains](http://postgis.net/docs/manual-2.2/ST_Contains.html)', or '[within](http://postgis.net/docs/manual-2.2/ST_Within.html)'.
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#### Returns
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A table with the following columns:
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Column Name | Description
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--- | ---
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the_geom | a point geometry (e.g., a point on a US Census tract)
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geom_ref | a string identifier for the geometry (e.g., the geoid of a US Census tract)
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#### Example
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Get Census tracts which intersect within 10 miles of Downtown, Colorado. In the Editor, you can simple use "Table from Query" to turn the result into a new dataset.
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```sql
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SELECT *
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FROM OBS_GetPointsByPointAndRadius(
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CDB_LatLng(39.7392, -104.9903), -- Denver, Colorado
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10000 * 1.609, -- 10 miles (10km * conversion to miles)
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'us.census.tiger.census_tract')
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```
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