举个例子：

import numpy as np
import pandas as pd

# Sample data:
df = pd.DataFrame({
    "session": np.repeat(np.arange(5), 4),
    "data": np.arange(20)
})

# Define the cutoffs for each session:
cutoffs = [3, 2, 4, 2, 1]
# Or use a dict: session -> cutoff

out = df.groupby("session").apply(lambda x: x.head(cutoffs[x.name]))
# x.name is the current session of whatever group is being worked on

输出：

session  data
session
0       0         0     0
        1         0     1
        2         0     2
1       4         1     4
        5         1     5
2       8         2     8
        9         2     9
        10        2    10
        11        2    11
3       12        3    12
        13        3    13
4       16        4    16

第二级指标为原始指标;您可以选择使用.droplevel(1)删除它