import pandas as pd import numpy as np from openpyxl import load_workbook path = r"C:\Users\fedel\Desktop\excelData\PhD_data.xlsx" book = load_workbook(path) writer = pd.ExcelWriter(path, engine = 'openpyxl') writer.book = book x3 = np.random.randn(100, 2) df3 = pd.DataFrame(x3) x4 = np.random.randn(100, 2) df4 = pd.DataFrame(x4) df3.to_excel(writer, sheet_name = 'x3') df4.to_excel(writer, sheet_name = 'x4') writer.save() writer.close()