熊猫从字符串中提取数字

Question

Given the following data frame:

import pandas as pd
import numpy as np
df = pd.DataFrame({'A':['1a',np.nan,'10a','100b','0b'],
                   })
df

    A
0   1a
1   NaN
2   10a
3   100b
4   0b

I'd like to extract the numbers from each cell (where they exist). The desired result is:

    A
0   1
1   NaN
2   10
3   100
4   0

I know it can be done with str.extract , but I'm not sure how.

Answer 1

Give it a regex capture group:

df.A.str.extract('(\d+)')

Gives you:

0      1
1    NaN
2     10
3    100
4      0
Name: A, dtype: object

Answer 2

要在上面的评论中回答@Steven G 的问题，这应该有效：

df.A.str.extract('(^\d*)')

Answer 3

您可以使用“分配”功能用您的结果替换您的列：

df = df.assign(A = lambda x: x['A'].str.extract('(\d+)'))