Python Pandas: Append Data to Existing Excel File (Openpyxl)

{/'title/': /'Python Pandas: Append Data to Existing Excel File (Openpyxl)/', /'description/': /'This code snippet demonstrates how to use Python's Pandas and Openpyxl libraries to append data to an existing Excel file. Learn how to efficiently process CSV files, filter data, and write results to a specific sheet within an Excel workbook./', /'keywords/': /'python, pandas, excel, openpyxl, append, data, csv, filter, write, excelwriter, sheet, workbook/', /'content/': /'import pandas as pd//nimport os//nimport re//nfrom openpyxl import load_workbook//n//noutput_folder = 'F:/自动验单数据/验本数据/'//noutput_file = None//n//nfor filename in os.listdir(folder_path)://n if re.match(file_format, filename)://n date_str = filename[11:19]//n file_path = os.path.join(folder_path, filename)//n yb_data = pd.read_csv(file_path, dtype=object, usecols=['发验机构', '上下行','发验时间'])//n data = yb_data[((yb_data['机构'] == '21506') & (yb_data['地市'] == '扬州市') & (yb_data['上下行'] == '上行'))]//n file_name = date_str + '验本数据.xlsx'//n //n if output_file is None://n output_file = os.path.join(output_folder, file_name)//n data.to_excel(output_file, index=False)//n else://n writer = pd.ExcelWriter(output_file, mode='a', engine='openpyxl')//n writer.book = load_workbook(output_file)//n writer.sheets = {ws.title: ws for ws in writer.book.worksheets}//n data.to_excel(writer, index=False, header=False, startrow=writer.sheets[/'Sheet1/'].max_row)//n writer.save()//n//nprint('匹配完成！')/