如何将空列添加到数据框? [英] How to add an empty column to a dataframe?

问题描述

向熊猫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类似的

What's the easiest way to add an empty column to a pandas DataFrame object? The best I've stumbled upon is something like

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

有不那么反常的方法吗?

Is there a less perverse method?

推荐答案

如果我理解正确，则应填写作业:

If I understand correctly, assignment should fill:

>>> 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

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