IoTDB-Quality

# PatternSymmetric

# Usage

This function is used to find all symmetric subseries in the input whose degree of symmetry is less than the threshold. The degree of symmetry is calculated by DTW. The smaller the degree, the more symmetrical the series is.

Name: PATTERNSYMMETRIC

Input Series: Only support a single input series. The type is INT32 / INT64 / FLOAT / DOUBLE

Parameter:

  • window: The length of the symmetric subseries. It's a positive integer and the default value is 10.
  • threshold: The threshold of the degree of symmetry. It's non-negative. Only the subseries whose degree of symmetry is below it will be output. By default, all subseries will be output.

Output Series: Output a single series. The type is DOUBLE. Each data point in the output series corresponds to a symmetric subseries. The output timestamp is the starting timestamp of the subseries and the output value is the degree of symmetry.

# Example

Input series:

+-----------------------------+---------------+
|                         Time|root.test.d1.s4|
+-----------------------------+---------------+
|2021-01-01T12:00:00.000+08:00|            1.0|
|2021-01-01T12:00:01.000+08:00|            2.0|
|2021-01-01T12:00:02.000+08:00|            3.0|
|2021-01-01T12:00:03.000+08:00|            2.0|
|2021-01-01T12:00:04.000+08:00|            1.0|
|2021-01-01T12:00:05.000+08:00|            1.0|
|2021-01-01T12:00:06.000+08:00|            1.0|
|2021-01-01T12:00:07.000+08:00|            1.0|
|2021-01-01T12:00:08.000+08:00|            2.0|
|2021-01-01T12:00:09.000+08:00|            3.0|
|2021-01-01T12:00:10.000+08:00|            2.0|
|2021-01-01T12:00:11.000+08:00|            1.0|
+-----------------------------+---------------+

SQL for query:

select patternsymmetric(s4, 'window'='5', 'threshold'='0') from root.test.d1

Output series:

+-----------------------------+----------------------------------------------------------------+
|                         Time|patternsymmetric(root.test.d1.s4, "window"="5", "threshold"="0")|
+-----------------------------+----------------------------------------------------------------+
|2021-01-01T12:00:00.000+08:00|                                                             0.0|
|2021-01-01T12:00:07.000+08:00|                                                             0.0|
+-----------------------------+----------------------------------------------------------------+

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