Scan_Normal_LCSS and Scan_LCSS functions

The Scan_Normal_LCSS and Scan_LCSS functions match the search pattern to the time series using the longest common subsequence formula.

Syntax

Scan_Normal_LCSS(
                 ts                  TimeSeries,
                 ident               LVARCHAR,
                 col_name            LVARCHAR,
                 begin_tstamp        DATETIME YEAR TO FRACTION(5),
                 end_tstamp          DATETIME YEAR TO FRACTION(5),
                 pattern             LIST (ROW (DOUBLE PRECISION) NOT NULL),
                 enlarge_threshold   DOUBLE PRECISION, 
                 normalized_delta    DOUBLE PRECISION,
                 epsilon             DOUBLE PRECISION, 
                 norm_lcss_threshold DOUBLE PRECISION) 
RETURNS LIST (SEARCHROW NOT NULL)

Scan_LCSS(
                 ts                  TimeSeries,
                 ident               LVARCHAR,
                 col_name            LVARCHAR,
                 begin_tstamp        DATETIME YEAR TO FRACTION(5),
                 end_tstamp          DATETIME YEAR TO FRACTION(5),
                 pattern             LIST (ROW (DOUBLE PRECISION) NOT NULL),
                 enlarge_threshold   DOUBLE PRECISION, 
                 normalized_delta    DOUBLE PRECISION,
                 epsilon             DOUBLE PRECISION, 
                 lcss_threshold      DOUBLE PRECISION) 
RETURNS LIST (SEARCHROW NOT NULL)

ts: The time series value for the specified primary key.
ident: A string identifier that is associated with the time series instance.
col_name: The name of the column in the TimeSeries data type from which to retrieve the values.
begin_stamp: The begin point of the range to search. Can be NULL, which represents the first element in the time series.
end_stamp: The end point of the range to search. Can be NULL, which represents the last element in the time series.
pattern: A search pattern that is returned by the ValueAsCollection or TSGetValueList function.
enlarge_threshold: A number that when multiplied by the pattern length specifies the size of the sliding window.
normalized_delta: The limit of the delta distance.
epsilon: The value of ϵ in the longest common subsequence formula.
norm_lcss_threshold: The high bound of the distance.
lcss_threshold: The high bound of the distance.

Usage

This function measures the longest common subsequence (LCSS) similarity between the subsequences of a time series and a pattern using a sliding window, where the length of the two subsequences is not necessarily the same. See Longest common subsequence.

Returns

A list of matches in a LIST data type that contains a SEARCHROW data type value for each match. See Scanning functions.