How Can Pandas Append Data to an Existing Excel Sheet Without Overwriting?

Writing to Existing Excel Files Without Overwriting: A Pandas Solution

When working with Excel files using pandas, writing to an existing sheet without overwriting the existing data can be a common challenge. This problem arises when pandas uses ExcelWriter's default behavior, which overwrites existing data by creating a new sheet.

To circumvent this issue, you can leverage ExcelWriter's "engine" parameter, which allows you to specify the underlying Excel engine. By setting this parameter to "openpyxl," you can integrate openpyxl's functionality with pandas.

Here's the code that addresses the problem:

import pandas
from openpyxl import load_workbook

# Load the existing Excel workbook
book = load_workbook('Masterfile.xlsx')

# Create an ExcelWriter object using the openpyxl engine
writer = pandas.ExcelWriter('Masterfile.xlsx', engine='openpyxl')

# Set the ExcelWriter's book attribute to the loaded workbook
writer.book = book

# Assign sheet names to the writer object's sheets attribute
writer.sheets = dict((ws.title, ws) for ws in book.worksheets)

# Write data to the existing sheet
data_filtered.to_excel(writer, "Main", cols=['Diff1', 'Diff2'])

# Save the updated workbook
writer.save()

By specifying the "openpyxl" engine, the modified code leverages openpyxl's ability to access existing sheets in the workbook. This allows pandas to append data to the "Main" sheet without overwriting the other tabs.

Note that you must ensure the "Main" sheet exists in the original workbook before running this code to avoid creating a new sheet if the sheet does not exist.

The above is the detailed content of How Can Pandas Append Data to an Existing Excel Sheet Without Overwriting?. For more information, please follow other related articles on the PHP Chinese website!