python - 使用字典转换 pandas 系列中列表的元素

Question

我有以下 Pandas 数据框:

1    ["Apple", "Banana"]
2    ["Kiwi"]
3    None
4    ["Apple"]
5    ["Banana", "Kiwi"]

和下面的字典:

{1: ["Apple", "Banana"],
2: ["Kiwi"]}

我现在想使用字典将列表中的所有条目映射到我的数据框中。结果应该是这样的:

1    [1]
2    [2]
3    None
4    [1]
5    [1, 2]

如何最有效地做到这一点？

Answer 1

方法一我正在使用 unnesting

d={z :  x for x , y in d.items() for z in y }
s=unnesting(s.to_frame().dropna(),[0])[0]\
   .map(d).groupby(level=0).apply(set).reindex(s.index)
Out[260]: 
0       {1}
1       {2}
2       NaN
3       {1}
4    {1, 2}
Name: 0, dtype: object

---

方法二循环

[set(d.get(y) for y in x) if  x is not None  else None for x in s ]
#s=[set(d.get(y) for y in x) if  x is not None  else None for x in s ]

Out[265]: [{1}, {2}, None, {1}, {1, 2}]

---

数据输入

s=pd.Series([["Apple", "Banana"],["Kiwi"],None,["Apple"],["Banana", "Kiwi"]])
d={1: ["Apple", "Banana"],
2: ["Kiwi"]}