observatory-extension/docs/v1/examples/01-measures-functions.md

Measures functions examples

• Add a measure to an empty numeric column based on point locations in your table.

UPDATE tablename
SET total_population = OBS_GetUSCensusMeasure(the_geom, 'Total Population')


- Add a measure to an empty numeric column based on polygons in your table

```SQL
UPDATE tablename
SET local_male_population = OBS_GetUSCensusMeasure(the_geom, 'Male Population')

• Add a measure to an empty numeric column based on point locations in your table

UPDATE tablename
SET median_home_value_sqft = OBS_GetMeasure(the_geom, 'us.zillow.AllHomes_MedianValuePerSqft')

• Add a measure to an empty column based on polygons in your table

UPDATE tablename
SET household_count = OBS_GetMeasure(the_geom, 'us.census.acs.B11001001')

• Add the Category to an empty column text column based on point locations in your table

UPDATE tablename
SET segmentation = OBS_GetCategory(the_geom, 'us.census.spielman_singleton_segments.X55')

• Obtain metadata that can augment with one additional column of US population data, using a boundary relevant for the geometry provided and latest timespan. Limit to only the most recent column most relevant to the extent & density of input geometries in tablename.

SELECT OBS_GetMeta(
  ST_SetSRID(ST_Extent(the_geom), 4326),
  '[{"numer_id": "us.census.acs.B01003001"}]',
  1, 1,
  COUNT(*)
) FROM tablename

• Obtain metadata that can augment with one additional column of US population data, using census tract boundaries.

SELECT OBS_GetMeta(
  ST_SetSRID(ST_Extent(the_geom), 4326),
  '[{"numer_id": "us.census.acs.B01003001", "geom_id": "us.census.tiger.census_tract"}]',
  1, 1,
  COUNT(*)
) FROM tablename

• Obtain metadata that can augment with two additional columns, one for total population and one for male population.

SELECT OBS_GetMeta(
  ST_SetSRID(ST_Extent(the_geom), 4326),
  '[{"numer_id": "us.census.acs.B01003001"}, {"numer_id": "us.census.acs.B01001002"}]',
  1, 1,
  COUNT(*)
) FROM tablename

• Validate metadata with two additional columns of US census data; using a boundary relevant for the geometry provided and the latest timespan. Limited to the most recent column, and the most relevant, based on the extent and density of input geometries in tablename.

SELECT OBS_MetadataValidation(
  ST_SetSRID(ST_Extent(the_geom), 4326),
  ST_GeometryType(the_geom),
  '[{"numer_id": "us.census.acs.B01003001"}, {"numer_id": "us.census.acs.B01001002"}]',
  COUNT(*)::INTEGER
) FROM tablename
GROUP BY ST_GeometryType(the_geom)

• Obtain population densities for every geometry in a table, keyed by cartodb_id:

WITH meta AS (
  SELECT OBS_GetMeta(
    ST_SetSRID(ST_Extent(the_geom), 4326),
    '[{"numer_id": "us.census.acs.B01003001"}]',
    1, 1, COUNT(*)
) meta FROM tablename)
SELECT id AS cartodb_id, (data->0->>'value')::Numeric AS pop_density
FROM OBS_GetData((SELECT ARRAY_AGG((the_geom, cartodb_id)::geomval) FROM tablename),
                 (SELECT meta FROM meta))

• Update a table with a blank numeric column called pop_density with population densities:

WITH meta AS (
  SELECT OBS_GetMeta(
    ST_SetSRID(ST_Extent(the_geom), 4326),
    '[{"numer_id": "us.census.acs.B01003001"}]',
    1, 1, COUNT(*)
) meta FROM tablename),
data AS (
  SELECT id AS cartodb_id, (data->0->>'value')::Numeric AS pop_density
  FROM OBS_GetData((SELECT ARRAY_AGG((the_geom, cartodb_id)::geomval) FROM tablename),
                   (SELECT meta FROM meta)))
UPDATE tablename
SET pop_density = data.pop_density
FROM data
WHERE cartodb_id = data.id

• Update a table with two measurements at once, population density and household density. The table should already have a Numeric column pop_density and household_density.

WITH meta AS (
  SELECT OBS_GetMeta(
    ST_SetSRID(ST_Extent(the_geom),4326),
    '[{"numer_id": "us.census.acs.B01003001"},{"numer_id": "us.census.acs.B11001001"}]',
    1, 1, COUNT(*)
) meta from tablename),
data AS (
  SELECT id,
     data->0->>'value' AS pop_density,
     data->1->>'value' AS household_density
  FROM OBS_GetData((SELECT ARRAY_AGG((the_geom, cartodb_id)::geomval) FROM tablename),
                   (SELECT meta FROM meta)))
UPDATE tablename
SET pop_density = data.pop_density,
    household_density = data.household_density
FROM data
WHERE cartodb_id = data.id

• Obtain population densities for every row of a table with FIPS code county IDs (USA).

WITH meta AS (
  SELECT OBS_GetMeta(
    ST_SetSRID(ST_Extent(the_geom), 4326),
    '[{"numer_id": "us.census.acs.B01003001", "geom_id": "us.census.tiger.county"}]'
) meta FROM tablename)
SELECT id AS fips, (data->0->>'value')::Numeric AS pop_density
FROM OBS_GetData((SELECT ARRAY_AGG(fips) FROM tablename),
                 (SELECT meta FROM meta))

• Update a table with population densities for every FIPS code county ID (USA). This table has a blank column called pop_density and fips codes stored in a column fips.

WITH meta AS (
  SELECT OBS_GetMeta(
    ST_SetSRID(ST_Extent(the_geom), 4326),
    '[{"numer_id": "us.census.acs.B01003001", "geom_id": "us.census.tiger.county"}]'
) meta FROM tablename),
data as (
  SELECT id AS fips, (data->0->>'value') AS pop_density
  FROM OBS_GetData((SELECT ARRAY_AGG(fips) FROM tablename),
                   (SELECT meta FROM meta)))
UPDATE tablename
SET pop_density = data.pop_density
FROM data
WHERE fips = data.id