How to add an empty Worksheet into an existing Workbook using Pandas ExcelWriter

Question

I am trying to add an empty excel sheet into an existing Excel File using python xlsxwriter.

Setting the formula up as follows works well.

workbook = xlsxwriter.Workbook(file_name)
worksheet_cover = workbook.add_worksheet("Cover")
Output4 = workbook
Output4.close()

But once I try to add further sheets with dataframes into the Excel it overwrites the previous excel:

with pd.ExcelWriter('Luther_April_Output4.xlsx') as writer:
    data_DifferingRates.to_excel(writer, sheet_name='Differing Rates')
    data_DifferingMonthorYear.to_excel(writer, sheet_name='Differing Month or Year')
    data_DoubleEntries.to_excel(writer, sheet_name='Double Entries')

How should I write the code, so that I can add empty sheets and existing data frames into an existing excel file.

Alternatively it would be helpful to answer how to switch engines, once I have produced the Excel file…

Thanks for any help!

Asked By: psy.lue

||

Source

Answer 1

You could use pandas.ExcelWriter with optional mode='a' argument for appending to existing Excel workbook.

You can also append to an existing Excel file:

>>> with ExcelWriter('path_to_file.xlsx', mode='a') as writer:`
...     df.to_excel(writer, sheet_name='Sheet3')`

However unfortunately, this requires using a different engine, since as you observe the ExcelWriter does not support the optional mode='a' (append). If you try to pass this parameter to the constructor, it raises an error.

So you will need to use a different engine to do the append, like openpyxl. You’ll need to ensure that the package is installed, otherwise you’ll get a “Module Not Found” error. I have tested using openpyxl as the engine, and it is able to append new a worksheet to existing workbook:

with pd.ExcelWriter(engine='openpyxl', path='Luther_April_Output4.xlsx', mode='a') as writer:
    data_DifferingRates.to_excel(writer, sheet_name='Differing Rates')
    data_DifferingMonthorYear.to_excel(writer, sheet_name='Differing Month or Year')
    data_DoubleEntries.to_excel(writer, sheet_name='Double Entries')

Answered By: David Zemens

Answer 2

If you’re not forced use xlsxwriter try using openpyxl. Simply pass ‘openpyxl’ as the Engine for the pandas built-in ExcelWriter class. I had asked a question a while back on why this works. It is helpful code. It works well with the syntax of pd.to_excel() and it won’t overwrite your already existing sheets.

from openpyxl import load_workbook
import pandas as pd

book = load_workbook(file_name)
writer = pd.ExcelWriter(file_name, engine='openpyxl')
writer.book = book
data_DifferingRates.to_excel(writer, sheet_name='Differing Rates')
data_DifferingMonthorYear.to_excel(writer, sheet_name='Differing Month or Year')
data_DoubleEntries.to_excel(writer, sheet_name='Double Entries') 

writer.save()

Answered By: MattR

Answer 3

I think you need to write the data into a new file. This works for me:

#  Write multiple tabs (sheets) into to a new file
import pandas as pd
from openpyxl import load_workbook

Work_PATH = r'C:PythonTest'+'\'
ar_source =  Work_PATH + 'Test.xlsx'
Output_Wkbk = Work_PATH + 'New_Wkbk.xlsx'

# Need workbook from openpyxl load_workbook to enumerage tabs
#   is there another way with only xlsxwriter?
workbook = load_workbook(filename=ar_source)
# Set sheet names in workbook as a series.  
# You can also set the series manually tabs = ['sheet1', 'sheet2']
tabs = workbook.sheetnames  
print ('nWorkbook sheets: ',tabs,'n')

# Replace this function with functions for what you need to do
def default_col_width (df, sheetname, writer):
    # Note, this seems to use xlsxwriter as the default engine.
    for column in df:
        # map col width to col name. Ugh.
        column_width = max(df[column].astype(str).map(len).max(), len(column))
        # set special column widths 
        narrower_col = ['OS','URL'] #change to fit your workbook
        if column in narrower_col: column_width = 10
        if column_width >30: column_width = 30
        if column == 'IP Address': column_width = 15 #change for your workbook
        col_index = df.columns.get_loc(column)
        writer.sheets[sheetname].set_column(col_index,col_index,column_width)

    return  
    # Note nothing is returned.  Writer.sheets is global.

with pd.ExcelWriter(Output_Wkbk,engine='xlsxwriter') as writer:
    # Iterate throuth he series of sheetnames
    for tab in tabs:
        df1 = pd.read_excel(ar_source, tab).astype(str)
        # I need to trim my input
        df1.drop(list(df1)[23:],axis='columns', inplace=True, errors='ignore')

        try:
            # Set spreadsheet focus
            df1.to_excel(writer, sheet_name=tab, index = False, na_rep=' ')
            # Do something with the spreadsheet - Calling a function
            default_col_width(df1, tab, writer)  
        except:
            #  Function call failed so just copy tab with no changes
            df1.to_excel(writer, sheet_name=tab, index = False,na_rep=' ')

If I use the input file name as the output file name, it fails and erases the original. No need to save or close if you use With… it closes autmatically.

Answered By: Ishkatan

How to add an empty Worksheet into an existing Workbook using Pandas ExcelWriter

Question:

Answers: