===><一定要看官方文档，看了官方文档才明白是怎么回事
DataFrameGroupBy.agg(arg改为func好对应图片, *args, **kwargs)[source]
Aggregate using one or more operations over the specified axis.
| Parameters: |
func : function, string, dictionary, or list of string/functions
Function to use for aggregating the data. If a function, must either work when passed a DataFrame or when passed to DataFrame.apply. For a DataFrame, can pass a dict, if the keys are DataFrame column names.
Accepted combinations are:
- string function name.
- function.
- list of functions.
- dict of column names -> functions (or list of functions).
*args
Positional arguments to pass to func.--》为func服务的，单独没意义
**kwargs
Keyword arguments to pass to func.---》为func服务的，单独没意义
|
===>
这里的没有属性quantity，指的是quantity不是像‘sum’，‘max’，等函数式名称属性
对比下面两幅图===》传函数对象时，加可变参数有意义，传字符串时，不能加可变参数