向 pandas DataFrame 对象添加空列的最简单方法是什么？我偶然发现的最好的东西是

df['foo'] = df.apply(lambda _: '', axis=1)

有没有不那么反常的方法？

最佳答案

如果我理解正确，作业应该填写:

>>> import numpy as np
>>> import pandas as pd
>>> df = pd.DataFrame({"A": [1,2,3], "B": [2,3,4]})
>>> df
   A  B
0  1  2
1  2  3
2  3  4
>>> df["C"] = ""
>>> df["D"] = np.nan
>>> df
   A  B C   D
0  1  2   NaN
1  2  3   NaN
2  3  4   NaN

https://stackoverflow.com/questions/16327055/