pandas groupby 和 qcut [英] Pandas groupby and qcut

问题描述

有没有办法构造 Pandas groupby 和 qcut 命令以返回具有嵌套图块的列?具体来说，假设我有 2 组数据，并且我希望将 qcut 应用于每组，然后将输出返回到一列.这类似于 MS SQL Server 的 ntile() 命令，它允许 Partition by().

Is there a way to structure Pandas groupby and qcut commands to return one column that has nested tiles? Specifically, suppose I have 2 groups of data and I want qcut applied to each group and then return the output to one column. This would be similar to MS SQL Server's ntile() command that allows Partition by().

     A    B  C
0  foo  0.1  1
1  foo  0.5  2
2  foo  1.0  3
3  bar  0.1  1
4  bar  0.5  2
5  bar  1.0  3

在上面的数据框中，我想将 qcut 函数应用于 B，同时在 A 上进行分区以返回 C.

In the dataframe above I would like to apply the qcut function to B while partitioning on A to return C.

推荐答案

import pandas as pd
df = pd.DataFrame({'A':'foo foo foo bar bar bar'.split(),
                   'B':[0.1, 0.5, 1.0]*2})

df['C'] = df.groupby(['A'])['B'].transform(
                     lambda x: pd.qcut(x, 3, labels=range(1,4)))
print(df)

收益

     A    B  C
0  foo  0.1  1
1  foo  0.5  2
2  foo  1.0  3
3  bar  0.1  1
4  bar  0.5  2
5  bar  1.0  3

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