pandas.ExcelWriter ValueError: Append mode is not supported with xlsxwriter

Question

I want to add some records to an excel file and I use pandas.ExcelWriter to do this(http://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.ExcelWriter.html?highlight=excelwriter#pandas.ExcelWriter ):

import pandas as pd                                                     

df = pd.DataFrame(data={'a':[4], 'b':['corn'], 'c':[0.5]})              

with pd.ExcelWriter("test.xlsx", mode='a') as writer: 
            df.to_excel(writer) 

a, b, c are titles name of test.xlsx

run this program, raise a valueError:

ValueError                                Traceback (most recent call last)
<ipython-input-3-c643d22b4217> in <module>
----> 1 with pd.ExcelWriter("test.xlsx", mode='a') as writer:
      2     df.to_excel(writer)
      3 

~/anaconda/lib/python3.6/site-packages/pandas/io/excel.py in __init__(self, path, engine, date_format, datetime_format, mode, **engine_kwargs)
   1935 
   1936         if mode == 'a':
-> 1937             raise ValueError('Append mode is not supported with xlsxwriter!')
   1938 
   1939         super(_XlsxWriter, self).__init__(path, engine=engine,

ValueError: Append mode is not supported with xlsxwriter!

I don't know why?

Answer 1

Try with this:

with pd.ExcelWriter("existing_file_name.xlsx", engine="openpyxl", mode="a") as writer:
    df.to_excel(writer, sheet_name="name", startrow=num, startcol=num)

You need to specify the engine as "openpyxl".