python 创建一个空dataframe 然后添加行数据

import pandas as pdimport reimport mathdframe1 = pd.read_excel("window regulator分析报告数据对比源.xlsx", sheetname="Sheet1") #读取数据dframe2 = pd.read_excel("window regulator分析报告数据对比源.xlsx", sheetname="Sheet2")#dframe1["sku"] ="#" #添加一列数据，初始化为#df = pd.DataFrame(columns = ["ebayno", "p_sku", "sale", "sku"]) #创建一个空的dataframe# print(df)sku = dframe2.sku.valuesp_skus = dframe2.p_sku.values# print(p_skus)i = 0for ps in p_skus :    dframe1.loc[dframe1.p_sku == ps,"sku"] = sku[i]    # print(dframe1.loc[dframe1.p_sku == ps])    df = df.append(dframe1.loc[dframe1.p_sku == ps], ignore_index=True)  #忽略索引,往dataframe中插入一行数据    # print(df)    i = i + 1# print(dframe1)# print(sku.values) #将series变成数组print(df)df = df[["sku","ebayno","sale"]] #选取指定的列df.to_csv("std.csv",encoding="gbk",index=False ) #写入到csv时，不要将索引写入index = False