pandas :groupby 后的样本组 [英] pandas: sample groups after groupby

问题描述

如何在 Pandas 的 groupby 之后对组进行采样?假设我想在 groupby 之后获得前半组.

How can I sample groups after a groupby in pandas? Say I want to get the first half of groups after groupby.

In [194]: df = pd.DataFrame({'name':['john', 'george', 'john','andrew','Daniel','george','andrew','Daniel'], 'hits':[12,34,13,23,53,47,20,48]})
In [196]: grouped = df.groupby('name')

分组中有 'john'、'george'、'andrew'、'daniel' 4 个组，我有兴趣从 4 个组中取出 2 个组.没关系它返回哪 2 个组.

There are 'john', 'george', 'andrew', 'daniel' 4 groups in grouped and I'm interested in getting 2 groups out of the 4. It doesn't matter which 2 groups it returns.

非常感谢.

推荐答案

您可以提前对名称进行采样，并仅对所选名称进行分组:

You can sample the names ahead of time and only group the chosen names:

selected_names = np.random.choice(df.name.unique(),2,replace = False)
grouped = df[df.name.isin(selected_names)].groupby('name')

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