python - 解析错误，更新 1 行中的多个列

Question

输入到pd.read_clipboard()

Ratanhia ,30c x2, 200c x2
Aloe ,30c x2, 200c x2
Nitric Acid ,30c x2, 200c x 2
Sedum Acre ,200c x2, 30c x2
Paeonia ,200c x2, 30c x2
Sulphur ,200c x2, 30c x2
Hamamelis ,30c x1, 200c x1
Aesculus ,30c x1, 200c x1⁠⁠⁠⁠

代码:

import pandas as pd

df = pd.read_clipboard(header=None, sep=',')
df.columns = ['Medicine','power30c','power200c']
df.power30c=df.power30c.apply(lambda x: x[-1])
df.power200c=df.power200c.apply(lambda x: x[-1])
print df

输出:

       Medicine power30c power200c
0     Ratanhia         2         2
1         Aloe         2         2
2  Nitric Acid         2         2
3   Sedum Acre         2         2
4      Paeonia         2         2
5      Sulphur         2         2
6    Hamamelis         1         1
7     Aesculus         1         �

问题:

1. 为什么 ... 在最后一行？
2. 如何在 1 行中修改超过 1 列？

df[['power30c','power200c']] = df[['power30c','power200c']].apply(lambda x: x[-1])

Throws error:

ValueError: Length mismatch: Expected axis has 1 elements, new values have 3 elements

Python 版本:2.7，Pandas:0.19，IPython:4

Answer 1

你需要参数skipinitialspace:

df = pd.read_clipboard(sep=',',
                       names=['Medicine','power30c','power200c'], 
                       skipinitialspace=True)
print (df)
       Medicine power30c power200c
0     Ratanhia    30c x2   200c x2
1         Aloe    30c x2   200c x2
2  Nitric Acid    30c x2  200c x 2
3   Sedum Acre   200c x2    30c x2
4      Paeonia   200c x2    30c x2
5      Sulphur   200c x2    30c x2
6    Hamamelis    30c x1   200c x1
7     Aesculus    30c x1   200c x1

然后 indexing with str :

df[['power30c','power200c']] = df[['power30c','power200c']].apply(lambda x: x.str[-1])
print (df)
       Medicine power30c power200c
0     Ratanhia         2         2
1         Aloe         2         2
2  Nitric Acid         2         2
3   Sedum Acre         2         2
4      Paeonia         2         2
5      Sulphur         2         2
6    Hamamelis         1         1
7     Aesculus         1         1