def append_df_to_excel(filename, df, sheet_name='Sheet1', startrow=None,
                           truncate_sheet=False, 
                           **to_excel_kwargs):
        """
        Append a DataFrame [df] to existing Excel file [filename]
        into [sheet_name] Sheet.
        If [filename] doesn't exist, then this function will create it.
    
        Parameters:
          filename : File path or existing ExcelWriter
                     (Example: '/path/to/file.xlsx')
          df : dataframe to save to workbook
          sheet_name : Name of sheet which will contain DataFrame.
                       (default: 'Sheet1')
          startrow : upper left cell row to dump data frame.
                     Per default (startrow=None) calculate the last row
                     in the existing DF and write to the next row...
          truncate_sheet : truncate (remove and recreate) [sheet_name]
                           before writing DataFrame to Excel file
          to_excel_kwargs : arguments which will be passed to `DataFrame.to_excel()`
                            [can be dictionary]
    
        Returns: None
    
        (c) [MaxU](https://stackoverflow.com/users/5741205/maxu?tab=profile)
        """
        from openpyxl import load_workbook
    
        # ignore [engine] parameter if it was passed
        if 'engine' in to_excel_kwargs:
            to_excel_kwargs.pop('engine')
    
        writer = pd.ExcelWriter(filename, engine='openpyxl')
    
        # Python 2.x: define [FileNotFoundError] exception if it doesn't exist 
        try:
            FileNotFoundError
        except NameError:
            FileNotFoundError = IOError
    
    
        try:
            # try to open an existing workbook
            writer.book = load_workbook(filename)
            
            # get the last row in the existing Excel sheet
            # if it was not specified explicitly
            if startrow is None and sheet_name in writer.book.sheetnames:
                startrow = writer.book[sheet_name].max_row
    
            # truncate sheet
            if truncate_sheet and sheet_name in writer.book.sheetnames:
                # index of [sheet_name] sheet
                idx = writer.book.sheetnames.index(sheet_name)
                # remove [sheet_name]
                writer.book.remove(writer.book.worksheets[idx])
                # create an empty sheet [sheet_name] using old index
                writer.book.create_sheet(sheet_name, idx)
            
            # copy existing sheets
            writer.sheets = {ws.title:ws for ws in writer.book.worksheets}
        except FileNotFoundError:
            # file does not exist yet, we will create it
            pass
    
        if startrow is None:
            startrow = 0
    
        # write out the new sheet
        df.to_excel(writer, sheet_name, startrow=startrow, **to_excel_kwargs)
    
        # save the workbook
        writer.save()

pathExport = r"F:\PYTHON\NB-Suite_python39\MNE\outputData\df.xlsx"
df1 = pd.DataFrame({'numbers': [1, 2, 3],
                    'colors': ['red', 'white', 'blue'],
                    'colorsTwo': ['yellow', 'white', 'blue']
                    })

append_df_to_excel(pathExport, df1, sheet_name="DF1", index=False, startcol=0, startrow=0)

Traceback (most recent call last):
  File "<input>", line 83, in <module>
  File "<input>", line 46, in append_df_to_excel
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\site-packages\openpyxl\reader\excel.py", line 315, in load_workbook
    reader = ExcelReader(filename, read_only, keep_vba,
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\site-packages\openpyxl\reader\excel.py", line 124, in __init__
    self.archive = _validate_archive(fn)
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\site-packages\openpyxl\reader\excel.py", line 96, in _validate_archive
    archive = ZipFile(filename, 'r')
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\zipfile.py", line 1257, in __init__
    self._RealGetContents()
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\zipfile.py", line 1324, in _RealGetContents
    raise BadZipFile("File is not a zip file")
zipfile.BadZipFile: File is not a zip file

(Mar-09-2021, 03:26 PM)Baggio Wrote: Sure

Traceback (most recent call last):
  File "<input>", line 83, in <module>
  File "<input>", line 46, in append_df_to_excel
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\site-packages\openpyxl\reader\excel.py", line 315, in load_workbook
    reader = ExcelReader(filename, read_only, keep_vba,
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\site-packages\openpyxl\reader\excel.py", line 124, in __init__
    self.archive = _validate_archive(fn)
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\site-packages\openpyxl\reader\excel.py", line 96, in _validate_archive
    archive = ZipFile(filename, 'r')
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\zipfile.py", line 1257, in __init__
    self._RealGetContents()
  File "C:\Users\20180043\AppData\Local\Programs\Python\Python39\lib\zipfile.py", line 1324, in _RealGetContents
    raise BadZipFile("File is not a zip file")
zipfile.BadZipFile: File is not a zip file

writer = pd.ExcelWriter(filename, engine='openpyxl')`

writer = pd.ExcelWriter(filename, engine='openpyxl', mode='a')

(Mar-11-2021, 04:00 PM)buran Wrote: OK. Here is the solution - specify mode to be 'a', append

writer = pd.ExcelWriter(filename, engine='openpyxl', mode='a')

Alternatively, look at this one or this one where it loads the file before instantiating the pd.ExcelWriter.

I also post an answer on SO. I will appreciate if you upvote/accept the answer there