postgres检测零的重复模式 [英] postgres detect repeating patterns of zeros
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问题描述
在Postgres中,有没有一种方法可以在一个时间序列中检测长度为零的子序列至少3个?
Is there a way to detect subseries of zeros of length at least 3 within a time series in Postgres?
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
因此在此示例中,我想返回1-3年和6-9年,但不返回11年。 / p>
So in this example I'd like to return years 1-3 and 6-9, but not year 11.
推荐答案
这将做到:
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;
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