如何将前一个值复制并粘贴到 Excel 中的下一个空单元格？

Question

1. I have excel file

   | Name | City | Start Date | |Alex | Hong Kong | 2021-02-01 | |Annie | Hong Kong | | |Bob | Taipei | | |Lucy | Tokyo | | |David | London | 2021-07-01 | |Kate | New York | | |Cathrine | London | | |Rose | Hong Kong | | |Mary | Hong Kong | 2021-09-01 | |Johnny | London | | |Roy | Taipei | |

2. I want to use python auto update the start date in empty cell like as below result.

    | Name | City | Start Date | |Alex | Hong Kong | 2021-02-01 | |Annie | Hong Kong | 2021-02-01 | |Bob | Taipei | 2021-02-01 | |Lucy | Tokyo | 2021-02-01 | |David | London | 2021-07-01 | |Kate | New York | 2021-07-01 | |Cathrine | London | 2021-07-01 | |Rose | Hong Kong | 2021-07-01 | |Mary | Hong Kong | 2021-09-01 | |Johnny | London | 2021-09-01 | |Roy | Taipei | 2021-09-01 |

3. I use openpyxl read excel file

   df = pd.read_excel('C:/Users/Data.xlsx')

4. How to copy and paste the previous start date value to next empty cell?

    col = df['Start Date'] = np.where(df['Start Date'].isnull())

Answer 1

You can do it like this:

for i, d in enumerate(df['Start Date']):
    if d.strip() == '':
        df.at[i,'Start Date'] = df.at[i-1,'Start Date']

Assuming your date fields are string. You probably have to adjust to your exact formatting.