Pandas GroupBy.agg() 抛出 TypeError：aggregate() 缺少 1 个必需的位置参数：'arg'
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Pandas GroupBy.agg() throws TypeError: aggregate() missing 1 required positional argument: 'arg'
提问by user3476463
I'm trying to create multiple aggregations of the same field. I'm working in pandas, in python3.7. The syntax seems pretty straightforward based on the documentation:
我正在尝试创建同一字段的多个聚合。我在大Pandas工作，在 python3.7 中。根据文档，语法似乎非常简单：
https://pandas-docs.github.io/pandas-docs-travis/user_guide/groupby.html#named-aggregation
https://pandas-docs.github.io/pandas-docs-travis/user_guide/groupby.html#named-aggregation
I do not see why I'm getting the error below. Could someone please point out the issue and tell me how to fix it?
我不明白为什么会收到以下错误。有人可以指出问题并告诉我如何解决吗？
code:
代码：
qt_dy.groupby('date').agg(std_qty=('qty','std'),mean_qty=('qty','mean'),)
error:
错误：
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-62-6bb3aabf313f> in <module>
5
6 qt_dy.groupby('date')\
----> 7 .agg(std_qty=('qty','std'),mean_qty=('qty','mean'))
TypeError: aggregate() missing 1 required positional argument: 'arg'
回答by cs95
Looks like you're trying to use aggwith Named aggregations—this is a supported feature from v0.25 and above ONLY.
就像你看起来正在尝试使用agg与命名聚合-这是从v0.25支持的功能和上面只。
For older versions, you will need to use the list of tuples format:
对于旧版本，您需要使用元组列表格式：
qt_dy.groupby('date')['qty'].agg([('std_qty','std'), ('mean_qty','mean')])
Or, to aggregate multiple columns, a dictionary:
或者，要聚合多列，字典：
qt_dy.groupby('date').agg({'qty': [('std_qty','std'), ('mean_qty','mean')]})
For more information, take a look at my answer here.
有关更多信息，请在此处查看我的回答。
