从索引列中的行中提取最后一个单词

Question

我需要关于如何从索引值中提取最后一个单词的建议

我的数据集看起来像

                                                  Exercise 1        Exercise 2  ....
Homeworks                             Teacher      

/Users/school/Maths/Exercises on LD       GK         This exercise...   The second exercise needs ...         
... rows ...                              GK
/Users/school/Maths/Exercises on DE       MG
... rows ...                              MG
/Users/school/Maths/Exercises on GE       GD
... rows ...                              GD

和其他类似路径的名称。练习1和练习2是列；作业和教师是索引列

我需要按如下方式重命名索引列中的值（预期输出）：

                           Exercise 1        Exercise 2  ....
   Homeworks    Teacher                               
    
    LD             GK        This exercise...   The second exercise needs ...
    ... rows ...   GK
    DE             MG
    ... rows ...   MG
    GE             GD
    ... rows ...   GD

我已经这样做了：

df.index = pd.MultiIndex.from_arrays([df.index.str.extract('\s(\w)\/$')[0]], 
                                         names=['Homeworks', 'Teacher'])

我不得不使用多重索引，因为我有两列作为索引。 你能告诉我怎样才能拿到上面的桌子吗

Answer 1

鉴于以下情况：

import pandas as pd

data = {'Homeworks': ['//Users//school//Maths//Exercises1 on LD', '//Users//school//Maths//Exercises2 on DE', '//Users//school//Maths//Exercises3 on GE'],
        'Teacher': ['GK', 'MG', 'GD'],
        'Exercise 1': ['This exercise', 'This exercise', 'This exercise'],
        'Exercise 2': ['The second exercise needs', 'The second exercise needs', 'The second exercise needs']}

df = pd.DataFrame(data)
df.set_index(['Homeworks', 'Teacher'], inplace=True)

# display(df)
                                                     Exercise 1                 Exercise 2
Homeworks                                Teacher                                          
//Users//school//Maths//Exercises1 on LD GK       This exercise  The second exercise needs
//Users//school//Maths//Exercises2 on DE MG       This exercise  The second exercise needs
//Users//school//Maths//Exercises3 on GE GD       This exercise  The second exercise needs

更新df：

• 重置索引
• 从Homeworks的最后两个字母创建一个新列
• （可选）从Homeworks提取路径
• 设置新索引

df.reset_index(inplace=True)
df['Drives'] = df.Homeworks.str[-2:]  # take the last to letters
df['Paths'] = df.Homeworks.str.split(expand=True)[0]  # split on space and take the value at index 0
df.drop(columns=['Homeworks'], inplace=True)
df.set_index(['Drives', 'Teacher'], inplace=True)  # set the index

# display(df)
                   Exercise 1                 Exercise 2                               Paths
Drives Teacher                                                                              
LD     GK       This exercise  The second exercise needs  //Users//school//Maths//Exercises1
DE     MG       This exercise  The second exercise needs  //Users//school//Maths//Exercises2
GE     GD       This exercise  The second exercise needs  //Users//school//Maths//Exercises3

Answer 2

您可以循环“Homeworks”并将其指定给新名称

for i in range(0,len(df["Homeworks"])):
    df["Homeworks"][i] = newstring

正在从df[“Homeworks”][i]更新您的正则表达式字符串