Python:每组随机选择 [英] Python: Random selection per group

问题描述

说我有一个看起来像这样的数据框:

Say that I have a dataframe that looks like:

Name Group_Id
AAA  1
ABC  1
CCC  2
XYZ  2
DEF  3 
YYH  3

如何为每个Group_Id随机选择一个(或多个)行?假设我要每Group_Id次随机抽奖，我会得到:

How could I randomly select one (or more) row for each Group_Id? Say that I want one random draw per Group_Id, I would get:

Name Group_Id
AAA  1
XYZ  2
DEF  3

推荐答案

size = 2        # sample size
replace = True  # with replacement
fn = lambda obj: obj.loc[np.random.choice(obj.index, size, replace),:]
df.groupby('Group_Id', as_index=False).apply(fn)

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