Skip to content
Reference > Prepare Methods

segmentByLocalExtrema(x,y,dx,dataFilterLength,derivedFilterLength)

Definition

Integer segmentByLocalExtrema(Number x, Number y, Number dx, Number dataFilterLength, Number derivedFilterLength)

Description

segment data based on local extremas of function f(x,y)

Parameter Definition

Name Type Description
x Number Number array x
y Number Number array y
dx Number step size for calculating the derivate
dataFilterLength Number Filter length used in the low-pass filter to smooth the number array y. If the length is equal to 1, smoothing is skipped
derivedFilterLength Number Filter length used in the low-pass filter to smooth the derivate. If the length is equal to 1, smoothing is skipped

Example 1

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
CREATE TABLE input(x int, y int);
INSERT INTO input VALUES (1,50), (2,200), (3,400), (4,50), (5,250), (6,300);
CREATE TABLE result AS PREPARE *, segmentByLocalExtrema(x, y, 1, 1, 1) as segment from input;
Table input = SELECT * FROM input;
TABLE result = SELECT * FROM result;

// input = 
// +---------------+
// |     input     |
// +-------+-------+
// |x      |y      |
// |Integer|Integer|
// +-------+-------+
// |1      |50     |
// |2      |200    |
// |3      |400    |
// |4      |50     |
// |5      |250    |
// |6      |300    |
// +-------+-------+
// 
// result = 
// +-----------------------+
// |        result         |
// +-------+-------+-------+
// |x      |y      |segment|
// |Integer|Integer|Integer|
// +-------+-------+-------+
// |1      |50     |0      |
// |2      |200    |1      |
// |3      |400    |1      |
// |4      |50     |2      |
// |5      |250    |3      |
// |6      |300    |3      |
// +-------+-------+-------+
//