我想计算 SQLite 表中数据的移动平均值。我在MySQL中找到了几种方法,但在SQLite中找不到有效的方法。
在 SQL 中,我认为类似的事情应该可以做到(但是,我无法尝试......):
SELECT date, value,
avg(value) OVER (ORDER BY date ROWS BETWEEN 3 PRECEDING AND 3 FOLLOWING) as MovingAverageWindow7
FROM t ORDER BY date;
但是,我看到两个缺点:
- 这似乎不适用于 sqlite
- 如果前/后行上的几个日期的数据不连续,它会计算窗口上的移动平均值,该窗口比我实际想要的更宽,因为它仅基于周围行的数量。因此,应添加日期条件
事实上,我希望它计算每个日期的“价值”平均值,超过 +/-3 天(每周移动平均值)或 +/-15 天(每月移动平均值)
这是一个示例数据集:
CREATE TABLE t ( date DATE, value INTEGER );
INSERT INTO t (date, value) VALUES ('2018-02-01', 8);
INSERT INTO t (date, value) VALUES ('2018-02-02', 2);
INSERT INTO t (date, value) VALUES ('2018-02-05', 5);
INSERT INTO t (date, value) VALUES ('2018-02-06', 4);
INSERT INTO t (date, value) VALUES ('2018-02-07', 1);
INSERT INTO t (date, value) VALUES ('2018-02-10', 6);
INSERT INTO t (date, value) VALUES ('2018-02-11', 0);
INSERT INTO t (date, value) VALUES ('2018-02-12', 2);
INSERT INTO t (date, value) VALUES ('2018-02-13', 1);
INSERT INTO t (date, value) VALUES ('2018-02-14', 3);
INSERT INTO t (date, value) VALUES ('2018-02-15', 11);
INSERT INTO t (date, value) VALUES ('2018-02-18', 4);
INSERT INTO t (date, value) VALUES ('2018-02-20', 1);
INSERT INTO t (date, value) VALUES ('2018-02-21', 5);
INSERT INTO t (date, value) VALUES ('2018-02-28', 10);
INSERT INTO t (date, value) VALUES ('2018-03-02', 6);
INSERT INTO t (date, value) VALUES ('2018-03-03', 7);
INSERT INTO t (date, value) VALUES ('2018-03-04', 3);
INSERT INTO t (date, value) VALUES ('2018-03-08', 5);
INSERT INTO t (date, value) VALUES ('2018-03-09', 6);
INSERT INTO t (date, value) VALUES ('2018-03-15', 1);
INSERT INTO t (date, value) VALUES ('2018-03-16', 3);
INSERT INTO t (date, value) VALUES ('2018-03-25', 5);
INSERT INTO t (date, value) VALUES ('2018-03-31', 1);