Django amp; Postgres - percentile (median) and group by(姜戈amp;Postgres - 百分位数(中位数)和分组依据)
问题描述
我需要计算每个卖家 ID 的周期中位数(参见下面的简化模型).问题是我无法构建 ORM 查询.
I need to calculate period medians per seller ID (see simplyfied model below). The problem is I am unable to construct the ORM query.
型号
查询
ArrayField 聚合 (seller_id
) 来源
我认为我需要做的是沿着下面的路线
I think what I need to do is something along the lines below
以上示例源
Python 3.7.5、Django 2.2.8、Postgres 11.1
Python 3.7.5, Django 2.2.8, Postgres 11.1
推荐答案
您可以创建 Aggregate
类的 Median
子类,就像 Ryan Murphy (https://gist.github.com/rdmurphy/3f73c7b1826cacee34f6c2a82e2e2e).Median
然后就像 Avg
一样工作:
You can create a Median
child class of the Aggregate
class as was done by Ryan Murphy (https://gist.github.com/rdmurphy/3f73c7b1826cacee34f6c2a855b12e2e). Median
then works just like Avg
:
然后找到一个字段的中位数使用
Then to find the median of a field use
然后可用作 my_model_aggregate['period__median']
.
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