Python 如何为数据帧的每一行分配组名?
这是一个示例dfPython 如何为数据帧的每一行分配组名?,python,pandas,dataframe,Python,Pandas,Dataframe,这是一个示例df df = pd.DataFrame({'A' : ['foo', 'bar', 'foo', 'bar', 'foo', 'bar', 'foo', 'foo'], 'B' : ['one', 'one', 'two', 'three', 'two', 'two', 'one', 'three'], 'C' : np
df = pd.DataFrame({'A' : ['foo', 'bar', 'foo', 'bar',
'foo', 'bar', 'foo', 'foo'],
'B' : ['one', 'one', 'two', 'three',
'two', 'two', 'one', 'three'],
'C' : np.random.randn(8),
'D' : np.random.randn(8)
})
A B C D
0 foo one 1.215172 -0.861875
1 bar one -0.318147 0.384239
2 foo two 1.729844 -0.173781
3 bar three 0.331456 0.914334
4 foo two 2.038198 -0.354784
5 bar two 0.258204 -1.476305
6 foo one -0.338992 0.856365
7 foo three -0.311692. -0.159846
并按A和B分类
for name, group in df.groupby(['A', 'B']):
print(name)
print(group)
('bar', 'one')
A B C D
1 bar one -0.318147 0.384239
('bar', 'three')
A B C D
3 bar three 0.331456 0.914334
('bar', 'two')
A B C D
5 bar two 0.258204 -1.476305
('foo', 'one')
A B C D
0 foo one 1.215172 -0.861875
6 foo one -0.338992 0.856365
('foo', 'three')
A B C D
7 foo three -0.311692 -0.159846
('foo', 'two')
A B C D
2 foo two 1.729844 -0.173781
4 foo two 2.038198 -0.354784
我们现在有6个小组
问题:如何添加一个名为G的新列,并让其值是由行所属的组确定的组名(例如G1、G2…G6)
以下是df的最终外观:
A B C D G
0 foo one 1.215172 -0.861875 G4
1 bar one -0.318147 0.384239 G1
2 foo two 1.729844 -0.173781 G6
3 bar three 0.331456 0.914334 G2
4 foo two 2.038198 -0.354784 G6
5 bar two 0.258204 -1.476305 G3
6 foo one -0.338992 0.856365 G4
7 foo three -0.311692. -0.159846 G5
感谢您的帮助。我需要重新设定一个待定的公关基础,而这个问题正是促使我着手解决它的原因:-),这将最终为我们提供一个干净的方式来访问此信息。同时,组码实际上存在于groupby对象中,只是隐藏了一点:
In [97]: df["GN"] = df.groupby(["A","B"]).grouper.group_info[0]
In [98]: df["G"] = "G" + (df["GN"] + 1).astype(str)
In [99]: df
Out[99]:
A B C D GN G
0 foo one -1.245506 0.307395 3 G4
1 bar one 0.072989 -0.402182 0 G1
2 foo two 0.399269 0.794413 5 G6
3 bar three 0.475859 -0.685398 1 G2
4 foo two -0.463065 -0.222632 5 G6
5 bar two 0.696606 -0.999691 2 G3
6 foo one -1.211876 -0.368574 3 G4
7 foo three -0.936385 -1.067160 4 G5
你能发一个到那个公关的链接吗?;)非常感谢。正是我想要的。