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added function overload with subqueries input

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abelvm 2016-06-03 18:22:26 +02:00
parent 73d38bbbaa
commit 5183f5ff92
2 changed files with 48 additions and 3 deletions
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20
doc/07_gravity.md
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@ -1,11 +1,11 @@
## Gravity Model
### CDB_Gravity(t_id bigint[], t_geom geometry[], t_weight numeric[], s_id bigint[], s_geom geometry[], s_pop numeric[], target bigint, radius integer, minval numeric DEFAULT -10e307)
Gravity Models are derived from Newton's Law of Gravity and are used to predict the interaction between a group of populated areas (sources) and a specific target among a group of potential targets, in terms of an attraction factor (weight)
**CDB_Gravity** is based on the model defined in *Huff's Law of Shopper attraction (1963)*
### CDB_Gravity(t_id bigint[], t_geom geometry[], t_weight numeric[], s_id bigint[], s_geom geometry[], s_pop numeric[], target bigint, radius integer, minval numeric DEFAULT -10e307)
#### Arguments
| Name | Type | Description |
@ -20,8 +20,22 @@ Gravity Models are derived from Newton's Law of Gravity and are used to predict
| radius | integer | Radius in meters around the target under study that will be taken into account|
| minval (optional) | numeric | Lowest accepted value of weight, defaults to numeric min_value |
### CDB_Gravity( target_query text, weight_column text, source_query text, pop_column text, target bigint, radius integer, minval numeric DEFAULT -10e307)
#### Returns
#### Arguments
| Name | Type | Description |
|------|------|-------------|
| target_query | text | Query that defines targets |
| weight_column | text | Column name of weights |
| source_query | text | Query that defines sources |
| pop_column | text | Column name of population |
| target | bigint | cartodb_id of the target under study |
| radius | integer | Radius in meters around the target under study that will be taken into account|
| minval (optional) | numeric | Lowest accepted value of weight, defaults to numeric min_value |
### Returns
| Column Name | Type | Description |
|-------------|------|-------------|

31
src/pg/sql/07_gravity.sql
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CREATE OR REPLACE FUNCTION CDB_Gravity(
IN target_query text,
IN weight_column text,
IN source_query text,
IN pop_column text,
IN target bigint,
IN radius integer,
IN minval numeric DEFAULT -10e307
)
RETURNS TABLE(
the_geom geometry,
source_id bigint,
target_id bigint,
dist numeric,
h numeric,
hpop numeric) AS $$
DECLARE
t_id bigint[];
t_geom geometry[];
t_weight numeric[];
s_id bigint[];
s_geom geometry[];
s_pop numeric[];
BEGIN
EXECUTE 'WITH foo as('+target_query+') SELECT array_agg(cartodb_id), array_agg(the_geom), array_agg(' || weight_column || ') FROM foo' INTO t_id, t_geom, t_weight;
EXECUTE 'WITH foo as('+source_query+') SELECT array_agg(cartodb_id), array_agg(the_geom), array_agg(' || pop_column || ') FROM foo' INTO s_id, s_geom, s_pop;
RETURN QUERY
SELECT g.* FROM t, s, CDB_Gravity(t_id, t_geom, t_weight, s_id, s_geom, s_pop, target, radius, minval) g;
END;
$$ language plpgsql;
CREATE OR REPLACE FUNCTION CDB_Gravity(
IN t_id bigint[],
IN t_geom geometry[],