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Reference > Prepare Methods

interpolate(x,y,method)

Definition

String interpolate(Number x, Number y, String method)

Description

forward interpolation between the current data point (xi,yi) and its subsequent data point(xi+1,yi+1),(xi+2,yi+2)..., using the method specified, returns the coefficients of the line/curve(interpolant).
In the case of a linear interpolation, the function returns the intercept and slope of the interpolant.

Parameter Definition

Name Type Description
x Number the data to interpolate on the X-axis
y Number the data to interpolate on the Y-axis
method String the method used to interpolate the data, can be either linear or spline

Example 1

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CREATE TABLE input(symbol String, x int, y int);
INSERT INTO input VALUES ("CAT", 1, 2),("CAT", 2, 4),("CAT", 3, 10),("CAT", 4, 1),("CAT", 5, 20);
INSERT INTO input VALUES ("IBM", 1, 4),("IBM", 2, 6),("IBM", 3, 9),("IBM", 4, 2),("IBM", 5, 30);
CREATE TABLE result AS PREPARE *,interpolate(x,y,"linear") as linear, interpolate(x,y,"spline") as spline from input PARTITION BY symbol;
Table input = SELECT * FROM input;
TABLE result = SELECT * FROM result;

// input = 
// +----------------------+
// |        input         |
// +------+-------+-------+
// |symbol|x      |y      |
// |String|Integer|Integer|
// +------+-------+-------+
// |CAT   |1      |2      |
// |CAT   |2      |4      |
// |CAT   |3      |10     |
// |CAT   |4      |1      |
// |CAT   |5      |20     |
// |IBM   |1      |4      |
// |IBM   |2      |6      |
// |IBM   |3      |9      |
// |IBM   |4      |2      |
// |IBM   |5      |30     |
// +------+-------+-------+
// 
// result = 
// +--------------------------------------------------------------------------------------------------------------+
// |                                                    result                                                    |
// +------+-------+-------+-----------+---------------------------------------------------------------------------+
// |symbol|x      |y      |linear     |spline                                                                     |
// |String|Integer|Integer|String     |String                                                                     |
// +------+-------+-------+-----------+---------------------------------------------------------------------------+
// |CAT   |1      |2      |0.0,2.0    |38.5,-67.25,36.5,-5.75                                                     |
// |CAT   |2      |4      |-8.0,6.0   |-380.0,351.25,-103.0,9.75                                                  |
// |CAT   |3      |10     |37.0,-9.0  !null                                                                       |
// |CAT   |4      |1      |-75.0,19.0 !null                                                                       |
// |CAT   |5      |20     !null       !null                                                                       |
// |IBM   |1      |4      |2.0,2.0    |28.000000000000114,-45.33333333333354,25.500000000000114,-4.166666666666686|
// |IBM   |2      |6      |0.0,3.0    |-349.9999999999999,332.66666666666663,-100.5,9.833333333333334             |
// |IBM   |3      |9      |30.0,-7.0  !null                                                                       |
// |IBM   |4      |2      |-110.0,28.0!null                                                                       |
// |IBM   |5      |30     !null       !null                                                                       |
// +------+-------+-------+-----------+---------------------------------------------------------------------------+
//