如何取消pandas数据框答案

【问题标题】：How to unpivot pandas dataframe如何取消pandas数据框
【发布时间】：2021-11-06 04:51:26
【问题描述】：

我有一个 Pandas 数据框，如下所示：起始表：

Kode	Country	Procedure	male	male	female	female
Kode	Country	Procedure	two-year-old	three-year-old	two-year-old	three-year-old
1a	US	proc_1	4	6	3	6
1a	UK	proc_1	2	3	5	1
1b	US	proc_2	15	3	5	2
1b	UK	proc_2	8	4	7	3

CSV：

Code;Country;Procedure;male;male;female;female
Code;Country;Procedure;two-year-old;three-year-old;two-year-old;three-year-old
1a;US;proc_1;4;6;3;6
1a;UK;proc_1;2;3;5;1
1b;US;proc_2;15;3;5;2
1b;UK;proc_2;8;4;7;3

我的python代码：

df = pd.read_csv('test.csv', 
                 header=[0,1],delimiter= ';',
                 engine='python', 
                 encoding= 'unicode_escape')

事实上我有两个行标题如何旋转 pandas 数据框以获得以下结果？

结果表：

Code	Country	Procedure	Gender	Age	Frequency
1a	US	proc_1	male	two-year-old	4
1a	US	proc_1	male	three-year-old	6
1a	US	proc_1	female	two-year-old	3
1a	US	proc_1	female	three-year-old	6
1a	UK	proc_1	male	two-year-old	2
1a	UK	proc_1	male	three-year-old	3
1a	UK	proc_1	female	two-year-old	5
1a	UK	proc_1	female	three-year-old	1
1b	...

【问题讨论】：

嘿@dublin123，试试这个：pandas.pydata.org/docs/reference/api/pandas.pivot_table.html
这个所谓的栈

标签： python pandas dataframe pivot

【解决方案1】：

您可能想要go with melt，这与枢轴相反。

我们指定标识符变量：前三列
其余列成为值变量，我们为它们分配名称，并为新值列命名

import io
import pandas as pd

piv = pd.read_csv(io.StringIO("""Code;Country;Procedure;male;male;female;female
Code;Country;Procedure;two-year-old;three-year-old;two-year-old;three-year-old
1a;US;proc_1;4;6;3;6
1a;UK;proc_1;2;3;5;1
1b;US;proc_2;15;3;5;2
1b;UK;proc_2;8;4;7;3"""), header=[0, 1], delimiter=";")


unpivoted = piv.melt(id_vars=list(piv.columns[:3]),
                     var_name=['gender', 'age'],
                     value_name='frequency')

# cleanup the tupleized columns
unpivoted.columns = [(col[0] if isinstance(col, tuple) else col)
                     for col in unpivoted.columns]

【讨论】：