不确定熔融/堆叠/未堆叠的顺序以改变我的数据框架。

Question

我有一个多索引列数据。我希望保留现有索引，但将一个级别从多个索引列移到索引的子级别。

我想不出melt/stack/unstack/pivot的正确咒语是如何从我所拥有的转移到我想要的。Unstacking()把事情变成了一个系列，失去了原来的日期索引。

names = ['mike', 'matt', 'dave']
details = ['bla', 'foo', ]

columns = pd.MultiIndex.from_tuples((n,d) for n in names for d in details)
index = pd.date_range(start="2022-10-30",  end="2022-11-3" ,freq="d", )
have = pd.DataFrame(np.random.randint(0,100, size = (5,6)), index=index, columns=columns)
have
   

want_columns = details
want_index = pd.MultiIndex.from_product([index, names])
want = pd.DataFrame(np.random.randint(0,100, size = (15,2)), index=want_index, columns=want_columns)
want

​

​

Answer 1

将DataFrame.stack与level=0结合使用

print (have.stack(level=0))
                 bla  foo
2022-10-30 dave   88   18
           matt   49   55
           mike   92   45
2022-10-31 dave   33   27
           matt   53   41
           mike   24   16
2022-11-01 dave   48   19
           matt   94   75
           mike   11   19
2022-11-02 dave   16   90
           matt   14   93
           mike   38   72
2022-11-03 dave   80   15
           matt   97    2
           mike   11   94