python-polars 使用字典按列值将数据帧拆分为多个 df

Question

我想使用字典按唯一列值将单个 df 拆分为多个 df。下面的代码显示了如何使用 pandas 完成此操作。我如何在 polars 中执行以下操作？

import pandas as pd

#Favorite color of 10 people
df = pd.DataFrame({"Favorite_Color":["Blue","Yellow","Black","Red","Blue","Blue","Green","Red","Red","Blue"]})
print(df)

#split df into many dfs by Favorite_Color using dict
dict_of_dfs={key: df.loc[value] for key, value in df.groupby(["Favorite_Color"]).groups.items()}
print(dict_of_dfs)

Answer 1

Polars 为此提供了一个 DataFrame 方法：partition_by。使用 as_dict 关键字创建 DataFrame 字典。

df.partition_by(groups="Favorite_Color", as_dict=True)

{'Blue': shape: (4, 1)
┌────────────────┐
│ Favorite_Color │
│ ---            │
│ str            │
╞════════════════╡
│ Blue           │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ Blue           │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ Blue           │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ Blue           │
└────────────────┘,
'Yellow': shape: (1, 1)
┌────────────────┐
│ Favorite_Color │
│ ---            │
│ str            │
╞════════════════╡
│ Yellow         │
└────────────────┘,
'Black': shape: (1, 1)
┌────────────────┐
│ Favorite_Color │
│ ---            │
│ str            │
╞════════════════╡
│ Black          │
└────────────────┘,
'Red': shape: (3, 1)
┌────────────────┐
│ Favorite_Color │
│ ---            │
│ str            │
╞════════════════╡
│ Red            │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ Red            │
├╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ Red            │
└────────────────┘,
'Green': shape: (1, 1)
┌────────────────┐
│ Favorite_Color │
│ ---            │
│ str            │
╞════════════════╡
│ Green          │
└────────────────┘}