Merge branch 'develop' into add-spatial-markov

doc/08_interpolation.md

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+## Spacial interpolation
+
+Function to interpolate a numeric attribute of a point in a scatter dataset of points, using one of three methos:
+
+* [Nearest neighbor](https://en.wikipedia.org/wiki/Nearest-neighbor_interpolation)
+* [Barycentric](https://en.wikipedia.org/wiki/Barycentric_coordinate_system)
+* [IDW](https://en.wikipedia.org/wiki/Inverse_distance_weighting)
+
+### CDB_SpatialInterpolation (query text, point geometry, method integer DEFAULT 1, p1 integer DEFAULT 0, ps integer DEFAULT 0)
+
+#### Arguments
+
+| Name | Type | Description |
+|------|------|-------------|
+| query   | text | query that returns at least `the_geom` and a numeric value as `attrib` |
+| point   | geometry | The target point to calc the value |
+| method   | integer     | 0:nearest neighbor, 1: barycentric, 2: IDW|
+| p1   | integer     | IDW: limit the number of neighbors, 0->no limit|
+| p2   | integer     | IDW: order of distance decay, 0-> order 1|
+
+### CDB_SpatialInterpolation (geom geometry[], values numeric[], point geometry, method integer DEFAULT 1, p1 integer DEFAULT 0, ps integer DEFAULT 0)
+
+#### Arguments
+
+| Name | Type | Description |
+|------|------|-------------|
+| geom   | geometry[]  | Array of points's geometries |
+| values | numeric[]   | Array of points' values for the param under study|
+| point   | geometry | The target point to calc the value |
+| method   | integer     | 0:nearest neighbor, 1: barycentric, 2: IDW|
+| p1   | integer     | IDW: limit the number of neighbors, 0->no limit|
+| p2   | integer     | IDW: order of distance decay, 0-> order 1|
+
+### Returns
+
+| Column Name | Type | Description |
+|-------------|------|-------------|
+| value  | numeric | Interpolated value at the given point, `-888.888` if the given point is out of the boundaries of the source points set |
+
+
+#### Example Usage
+
+```sql
+with a as (
+    select
+        array_agg(the_geom) as geomin,
+        array_agg(temp::numeric) as colin
+    from table_4804232032
+)
+SELECT CDB_SpatialInterpolation(geomin, colin, CDB_latlng(41.38, 2.15),1) FROM a;
+```

doc/11_kmeans.md

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+## K-Means Functions
+
+### CDB_KMeans(subquery text, no_clusters INTEGER)
+
+This function attempts to find n clusters within the input data. It will return a table to CartoDB ids and 
+the number of the cluster each point in the input was assigend to.
+
+
+#### Arguments
+
+| Name | Type | Description |
+|------|------|-------------|
+| subquery | TEXT | SQL query that exposes the data to be analyzed (e.g., `SELECT * FROM interesting_table`). This query must have the geometry column name `the_geom` and id column name `cartodb_id` unless otherwise specified in the input arguments |
+| no\_clusters | INTEGER | The number of clusters to try and find |
+
+#### Returns
+
+A table with the following columns.
+
+| Column Name | Type | Description |
+|-------------|------|-------------|
+| cartodb\_id | INTEGER | The CartoDB id of the row in the input table.|
+| cluster\_no | INTEGER | The cluster that this point belongs to. |
+
+
+#### Example Usage
+
+```sql
+SELECT 
+    customers.*, 
+    km.cluster_no 
+    FROM cdb_crankshaft.CDB_Kmeans('SELECT * from customers' , 6) km, customers_3
+    WHERE customers.cartodb_id = km.cartodb_id
+```
+
+### CDB_WeightedMean(subquery text, weight_column text, category_column text)
+
+Function that computes the weighted centroid of a number of clusters by some weight column.
+
+### Arguments 
+
+| Name | Type | Description |
+|------|------|-------------|
+| subquery | TEXT | SQL query that exposes the data to be analyzed (e.g., `SELECT * FROM interesting_table`). This query must have the geometry column and the columns specified as the weight and category columns|
+| weight\_column | TEXT | The name of the column to use as a weight |
+| category\_column | TEXT | The name of the column to use as a category |
+
+### Returns 
+
+A table with the following columns.
+
+| Column Name | Type | Description |
+|-------------|------|-------------|
+| the\_geom | GEOMETRY | A point for the weighted cluster center |
+| class | INTEGER | The cluster class | 
+
+### Example Usage 
+
+```sql 
+SELECT ST_TRANSFORM(the_geom, 3857) as the_geom_webmercator, class 
+FROM cdb_weighted_mean('SELECT *, customer_value FROM customers','customer_value','cluster_no')
+```