如何将多值字典映射到多个 Pandas 列？

Question

以下相关示例并没有完全得到正确答案（但很接近）：Python Pandas Assign a Dictionary Value to a Dataframe Column Based on Dictionary Key

我正在寻找一种方法，最好是单行，将字典键映射到我的数据框列。如果键匹配，我们应该将每个值解包到相应的列中。

import pandas as pd
d1 = {1231: 'val1, val2, val3',
      1232: 'val1a, val2a, val3a'}

df = pd.DataFrame({'key': [1231, 1232]})
df[['val1', 'val2', 'val3']] = df['key'].apply(lambda x: d1.get(x))[0].split(', ')
df

# this will map the same values repeatedly
# and will break if the index is altered or removed

Answer 1

试试map 然后str.split

df[['val1', 'val2', 'val3']] = df['key'].map(d1).str.split(', ',expand=True).values
df
    key   val1   val2   val3
0  1231   val1   val2   val3
1  1232  val1a  val2a  val3a