python - 如何使用 Python 将特定的选定行拆分为多行

Question

我有一个示例数据框

import pandas as pd
import numpy as np

data = {"Key" : ["First Row", "Sample sample first row: a Row to be splitted $ 369", "Sample second row : a Depreciation $ 458", "Last Row"],
        "Value1" : [365, 265.0, np.nan, 256],
        "value2" : [789, np.nan, np.nan, np.nan]
}


df = pd.DataFrame(data)

print(df)

 
                                Key                           Value1      value2
0                            First Row                          365.0      789.0
1   Sample sample first row: a Row to be splitted $ 369         265.0       NaN
2   Sample second row : a Depreciation $ 458                     NaN        NaN
3    Last Row                                                   256.0       NaN

我确实知道使用 Split cell into multiple rows in pandas dataframe 将任何类别拆分为多行

我找不到在所选部分拆分一行字符串。

期望的输出

              Key                  Value1   value2
0        First Row                  365.0    789.0
1   Sample sample first row:        265.0     NaN
2   a Row to be splitted $            369     NaN
3   Sample second row :               NaN     NaN
4   Depreciation $                    458     NaN
5    Last Row                       256.0     NaN

Answer 1

拆分、分解、提取和更新

我们可以在一个或多个空格字符上拆分列Key，前面有:，然后分解 Key 上的数据帧，接下来提取 Key 列中的数字，这些数字前面有 $ 符号并更新 Value1

中对应的值

df1 = df.assign(Key=df['Key'].str.split(r'(?<=:)\s+')).explode('Key')
df1['Value1'].update(df1['Key'].str.extract(r'\$\s*(\d+)', expand=False).astype(float))

---

>>> df1
                          Key  Value1  value2
0                   First Row   365.0   789.0
1    Sample sample first row:   265.0     NaN
1  a Row to be splitted $ 369   369.0     NaN
2         Sample second row :     NaN     NaN
2        a Depreciation $ 458   458.0     NaN
3                    Last Row   256.0     NaN