我有以下熊猫DataFrame：
import pandas as pd
import numpy as np
data = 'filename.csv'
df = pd.DataFrame(data)
df
one two three four five
a 0.469112 -0.282863 -1.509059 bar True
b NaN 1.224234 7.823421 bar False
c -1.135632 1.212112 -0.173215 bar False
d NaN NaN NaN NaN True
e 0.119209 -1.044236 -0.861849 bar True
f -2.104569 -0.494929 1.071804 bar False
我只想创建一个新列“ oneplus20”，以便将浮点
20.0添加到列“ one”中的每个单元格中。所以，我尝试df['oneplus20'] = df.apply(lambda row: row['one'] + 20, axis=1)
这行不通。我很困惑为什么没有。
做这样的事情的正确方法是什么？
最佳答案
尝试这个：
df['oneplus20'] = df['one'] + 20.0
演示：
In [36]: df['oneplus20'] = df['one'] + 20.0
In [37]: df
Out[37]:
one two three four five oneplus20
a 0.469112 -0.282863 -1.509059 bar True 20.469112
b NaN 1.224234 7.823421 bar False NaN
c -1.135632 1.212112 -0.173215 bar False 18.864368
d NaN NaN NaN NaN True NaN
e 0.119209 -1.044236 -0.861849 bar True 20.119209
f -2.104569 -0.494929 1.071804 bar False 17.895431
或者，如果您想将NaN替换为零：
In [45]: df['oneplus20'] = df['one'].fillna(0) + 20.0
In [46]: df
Out[46]:
one two three four five oneplus20
a 0.469112 -0.282863 -1.509059 bar True 20.469112
b NaN 1.224234 7.823421 bar False 20.000000
c -1.135632 1.212112 -0.173215 bar False 18.864368
d NaN NaN NaN NaN True 20.000000
e 0.119209 -1.044236 -0.861849 bar True 20.119209
f -2.104569 -0.494929 1.071804 bar False 17.895431
关于python - Pandas :从旧创建新列，添加值，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/38001588/