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cleanup, starting to remove SELECT examples

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andrewxhill
2016-05-10 16:01:39 -04:00
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doc/measures_functions.md
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# Measures Functions
[Data Observatory Measures](/cartodb-platform/dataobservatory/overview/#measures-methods) allow you to access geospatial measures for analysis workflows. Measures are used by sending an identifier or a geometry (Point or Polygon) and receiving back a measure or absolute value for that location. Every measure contained in the [Data Catalog](https://cartodb.github.io/bigmetadata/observatory.pdf) can be accessed through the CartoDB Editor.
[Data Observatory Measures](/cartodb-platform/dataobservatory/overview/#measures-methods) are the numerical location data you can access. The Measure Functions allow you to access individual measures to augment your own data or integrate in your analysis workflows. Measures are used by sending an identifier or a geometry (Point or Polygon) and receiving back a Measure (an absolute value) for that location.
## OBS_GetUSCensusMeasure(point_geometry, measure_name);
There are hundreds of Measures and the list is growing with each release. You can currently discover and learn about measures contained in the Data Observatory by downloading our [Data Catalog](https://cartodb.github.io/bigmetadata/observatory.pdf).
The ```OBS_GetUSCensusMeasure(point_geometry, measure_name)``` function returns a measure based on a subset of the US Census variables at a point location. The ```OBS_GetUSCensusMeasure``` function is limited to only a subset of all measures that are available in the Data Observatory, to access the full list, use the ```OBS_GetMeasure``` function below.
We show here how you can access Measures through the CartoDB Editor. The same methods will work if you are using the CartoDB Platform to develop your application. We encourage you to use table modifying methods (UPDATE and INSERT) over dynamic methods (SELECT).
## OBS_GetUSCensusMeasure(point geometry, measure_name text);
The ```OBS_GetUSCensusMeasure(point_geometry, measure_name)``` function returns a measure based on a subset of the US Census variables at a point location. The ```OBS_GetUSCensusMeasure``` function is limited to only a subset of all Measures that are available in the Data Observatory, to access the full list, use the ```OBS_GetMeasure``` function below.
#### Arguments
Name |Description
--- | ---
point_geometry | a WGS84 point geometry (the_geom)
measure_name | a human readable string name of a US Census variable. The list of measure_names is [available in the glossary](/cartodb-platform/dataobservatory/glossary/#obsgetuscensusmeasure-names-table).
measure_name | a human readable name of a US Census variable. The list of measure_names is [available in the glossary](/cartodb-platform/dataobservatory/glossary/#obsgetuscensusmeasure-names-table).
normalize | for measures that are are **sums** (e.g. population) the default normalization is 'area' and response comes back as a rate per square kilometer. Other options are 'denominator', which will use the denominator specified in the
#### Returns
@@ -30,12 +34,6 @@ Add a Measure to an empty column based on point locations in your table
UPDATE tablename SET local_male_population = OBS_GetUSCensusMeasure(the_geom, 'Male Population')
```
Get a measure at a single point location
```SQL
SELECT OBS_GetUSCensusMeasure(CDB_LatLng(40.7, -73.9), 'Male Population')
```
<!--
Should add the SQL API call here too
-->
@@ -82,7 +80,7 @@ Should add the SQL API call here too
## OBS_GetUSCensusCategory(point_geometry, measure_name);
The ```OBS_GetUSCensusCategory(point_geometry, category_name)``` function returns a categorical measure based on a subset of the US Census variables at a point location. It requires a different function from ```OBS_GetUSCensusMeasure``` because this function will always return TEXT, whereas ```OBS_GetUSCensusMeasure``` will always returna NUMERIC value.
The ```OBS_GetUSCensusCategory(point_geometry, category_name)``` function returns a categorical measure based on a subset of the US Census variables at a point location. It requires a different function from ```OBS_GetUSCensusMeasure``` because this function will always return TEXT, whereas ```OBS_GetUSCensusMeasure``` will always returna NUMERIC value.
#### Arguments