nPath Greedy Pattern Matching - Teradata Vantage

Machine Learning Engine Analytic Function Reference

Product
Teradata Vantage
Release Number
8.00
1.0
Published
May 2019
Language
English (United States)
Last Update
2019-11-22
dita:mapPath
blj1506016597986.ditamap
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dita:id
B700-4003
lifecycle
previous
Product Category
Teradata Vantage™

The nPath function uses greedy pattern matching, finding the longest available match despite any nongreedy operators in the pattern.

For example, consider the input table link2:

link2
userid title startdate enddate
21 Chief Exec Officer 1994-10-01 2005-02-28
21 Software Engineer 1996-10-01 2001-06-30
21 Software Engineer 1998-10-01 2001-06-30
21 Chief Exec Officer 2005-03-01 2007-03-31
21 Chief Exec Officer 2007-06-01 null

This query returns the following table:

SELECT job_transition_path, count(*) AS count1 FROM nPath@coprocessor (
  ON link2 PARTITION BY userid ORDER BY startdate
  USING
  Mode (NONOVERLAPPING)
  Pattern ('CEO.ENGR.OTHER*')
  Symbols (title1 ilike 'software eng%' AS ENGR,
    true AS OTHER,
    title1 ilike 'Chief Exec Officer' AS CEO)
  Result (accumulate(title OF ANY(ENGR,OTHER,CEO))
    AS job_transition_path)
) AS dt GROUP BY 1;
job_transition_path count
[Chief Exec Officer, Software Engineer, Software Engineer, Chief Exec Officer, Chief Exec Officer] 1

In the pattern, CEO matches the first row, ENGR matches the second row, and OTHER* matches the remaining rows:



This query returns the following table:

SELECT job_transition_path, count(*) AS count1 FROM nPath@coprocessor (
  ON link2 PARTITION BY userid ORDER BY startdate
  USING
  Mode (NONOVERLAPPING)
  Pattern ('CEO.ENGR.OTHER*.CEO')
  Symbols (title1 ilike 'software eng%' AS ENGR,
    true AS OTHER,
    title1 ilike 'Chief Exec Officer' AS CEO)
  Result (accumulate(title1 of ANY(ENGR,OTHER,CEO))
    AS job_transition_path)
) AS dt GROUP BY 1;
job_transition_path count
[Chief Exec Officer, Software Engineer, Software Engineer, Chief Exec Officer, Chief Exec Officer] 1

In the pattern, CEO matches the first row, ENGR matches the second row, OTHER* matches the next two rows, and CEO matches the last row: