在Postgres中,是否有方法在一个时间序列中检测长度至少为3的零点的子序列?
year value
--------------
1 0
2 0
3 0
4 33
5 72
6 0
7 0
8 0
9 0
10 25
11 0
12 56
13 37
所以在这个例子中,我想返回年份1-3和6-9,但不是11岁。
发布于 2014-10-23 19:28:40
这个人会做的:
WITH d(y,v) AS (VALUES
(1,0),(2,0),(3,0),(4,33),(5,72),
(6,0),(7,0),(8,0),(9,0),(10,25),
(11,0),(12,56),(13,37)
)
SELECT grp, numrange(min(y),max(y),'[]') as ys, count(*) as len
FROM (
/* group identifiers via running total */
SELECT y, v, g, sum(g) OVER (ORDER BY y) grp
FROM (
/* group boundaries */
SELECT y, v, CASE WHEN
v IS DISTINCT FROM lag(v) OVER (ORDER BY y) THEN 1
END g
FROM d) s
WHERE v=0) s
GROUP BY grp
HAVING count(*) >= 3;
https://stackoverflow.com/questions/26534920
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