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add NN(s) support

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abelvm 2016-09-20 12:57:41 +02:00
parent 756db707b5
commit 2ff20e596e
2 changed files with 17 additions and 6 deletions
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6
doc/08_interpolation.md
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@ -2,7 +2,7 @@
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)
* [Nearest neighbor(s)](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)
@ -15,7 +15,7 @@ Function to interpolate a numeric attribute of a point in a scatter dataset of p
| 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|
| p1 | integer | limit the number of neighbors, IDW: 0->no limit, NN: 0-> closest one|
| 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)
@ -28,7 +28,7 @@ Function to interpolate a numeric attribute of a point in a scatter dataset of p
| 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|
| p1 | integer | limit the number of neighbors, IDW: 0->no limit, NN: 0-> closest one|
| p2 | integer | IDW: order of distance decay, 0-> order 1|
### Returns

17
src/pg/sql/08_interpolation.sql
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@ -1,4 +1,4 @@
-- 0: nearest neighbor
-- 0: nearest neighbor (s)
-- 1: barymetric
-- 2: IDW
@ -51,11 +51,17 @@ DECLARE
output numeric;
BEGIN
output := -999.999;
-- nearest
-- nearest neighbors
-- p1: limit the number of neighbors, 0-> closest one
IF method = 0 THEN
IF p1 = 0 THEN
p1 := 1;
END IF;
WITH a as (SELECT unnest(geomin) as g, unnest(colin) as v)
SELECT a.v INTO output FROM a ORDER BY point<->a.g LIMIT 1;
SELECT avg(a.v) INTO output FROM a ORDER BY point<->a.g LIMIT p1::integer;
RETURN output;
-- barymetric
@ -121,6 +127,11 @@ BEGIN
SELECT sum(b.f)/sum(b.k) INTO output FROM b;
RETURN output;
-- krigin
ELSIF method = 3 THEN
END IF;
RETURN -777.777;