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How to export python dataframe into existing excel sheet and retain formatting?

I am trying to export a dataframe I've generated in Pandas to an Excel Workbook. I have been able to get that part working, but unfortunately no matter what I try, the dataframe goes into the workbook as a brand new worksheet.
What I am ultimately trying to do here is create a program that pulls API data from a website and imports it in an existing Excel sheet in order to create some sort of "live updating excel workbook". This means that the worksheet already has proper formatting, vba, and other calculated columns applied, and all of this would ideally stay the same except for the basic data in the dataframe I'm importing.
Anyway to go about this? Any direction at all would be quite helpful. Thanks.
Here is my current code:
file='testbook.xlsx'
writer = pd.ExcelWriter(file, engine = 'xlsxwriter')
df.to_excel(writer, sheet_name="Sheet1")
workbook = writer.book
worksheet = writer.sheets["Sheet1")
writer.save

In case u have both existing excel file and DataFrame in same format then you can simply import your exiting excel file into another DataFrame and concat both the DataFrames then save into new excel or existing one.
df1["df"] = pd.read_excel('testbook.xlsx')
df2["df"] = 1#your dataFrame
df = pd.concat([df1, df2])
df.to_excel('testbook.xlsx')
There are multiple ways of doing it if you want to do it completely using pandas library this will work.

Is it possible to append data to an xls file in Python?

I am trying to add a large dataset to an existing xls spreadsheet.
I'm currently writing to it using a pandas dataframe and the .to_excel() function, however this erases the existing data in the (multi-sheet) workbook. The existing spreadsheet is very large and complex,it also interacts with several other files, so I can't convert it to xlsx or read and rewrite all of the data, as I've seen some suggestions on other questions. I want the data that I am adding to be pasted starting from a set row in an existing sheet.

Yes , you can use the library xlsxwriter , link= https://xlsxwriter.readthedocs.io
code example :
import xlsxwriter
Name="MyFile"+".xlsx"
workbook = xlsxwriter.Workbook(Name)
worksheet = workbook.add_worksheet()
worksheet.write("A1", "Incident category".decode("utf-8"))
worksheet.write("B1", "Longitude".decode("utf-8"))
worksheet.write("C1", "Latitude".decode("utf-8"))
workbook.close()

Using pandas to replace data in excel sheet

I tried to come up with a way to copy data from a sheet in an excel file as
import pandas as pd
origionalFile = pd.ExcelFile('AnnualReport-V5.0.xlsx')
Transfers = pd.read_excel(origionalFile, 'Sheet1')
I have another excel file, which named 'AnnualReport-V6.0.xlsx', it has existing data in the sheet named 'Transfers', I tried to use the dataframe I created easily on to replace data in the sheet 'Transfers' in 'AnnualReport-V6.0.xlsx' from column B, leave column A as it is.
I did a few searches, the closest to what I want is this
Modifying an excel sheet in a excel book with pandas
but it does not allow me the keep column A in the original sheet (column A has some equations I do want to keep them), any idea how to do it? Thanks

Would reading column A and inserting it to the fresh data you want to write solve your problem?

Append a pandas dataframe to an existing excel table

I need some help with the following.
I currently use python pandas to open a massive spreadsheet every day (this spreadsheet is a report, hence every day the data inside the spreadsheet is different). Pandas dataframe allows me to quickly crunch the data and generate a final output table, with much less data than the initial excel file.
Now, on day 1, I would need to add this output dataframe (3 rows 10 columns) to a new excel sheet (let's say sheet 1).
On day 2, I would need to take the new output of the dataframe and append it to the existing sheet 1. So at the end of day 2, the table in sheet1 would have 6 rows and 10 columns.
On day 3, same thing. I will launch my python pnadas tool, read data from the excel report, generate an output dataframe 3x10 and append it again to my excel file.
I can't find a way to append to an existing excel table.
Could anybody help?
Many thanks in advance,
Andrea

If you use openpyxl's utilities for dataframes then you should be able to do everything you need with the existing workbook, assuming this fits into memory.
from openpyxl import load_workbook
from openpyxl.utils.dataframe import dataframe_to_rows
wb = load_workbook("C:\Andrea\master_file.xlsx")
ws = wb[SHEETNAME]
for row in dataframe_to_rows(dt_today):
ws.append(row)

How to add new column and row to .xls file using xlrd

How do you add a new column and/or row to a sheet in xlrd?
I have a .xls file that I read using open_workbook() and I need to add a new column("bouncebacks") to the first sheet then new rows to that sheet but I cannot find any functions in the xlrd documentation that shows how to add new rows and/or columns?
If I cant add a row/column in xlrd is there another way/library that allows me to add a row or column to an .xls file?
Can you show me how I can add a row and column to a sheet?
import xlrd
book = xlrd.open_workbook("abc.xls")
sheet = book.sheet_by_index(0)
# how do I add a new column("bouncebacks") to the sheet?
# how do I add a new row to the sheet?

xlrd reads xls files. xlwt creates new xls files. You need xlutils. Read this. Work through the tutorial that you'll find mentioned there.

xlrd is for reading from an .xls file. for writting to it use xlwt.