pandas - 用列表映射列并返回相应的列表

Question

import pandas as pd

pd.DataFrame({"a":["a","b","c"],"d":[1,2,3]})

给定一个数组["a","b","c","c"]，我希望它用于映射 col“a”，并获取[1,2,3,3]来自“d”列的输出。有没有一种简单的方法可以在不迭代行的情况下做到这一点？

标签： pandas

Answer 1

使用Series.reindexwith index bya转换为 index by DataFrame.set_index：

a = ["a","b","c","c"]

L = df.set_index('a').reindex(a)['d'].tolist()
print (L)
[1, 2, 3, 3]