熊猫在合并时默默地删除有用的行

Question

我正在尝试基于一个内部联接合并两个数据帧，当我将这些数据帧联接在一起时，它们会删除有用的行。

    import pandas as pd
    import zipfile

    read_advertiser_mapping = pd.read_csv("advertiserMarketMapping.csv",
                                          encoding="utf-8")
   print(read_advertiser_mapping.shape)
   (37, 2)

    read_dmc_static_zf = zipfile.ZipFile("DMC_Static_Conversions.zip")
    read_dmc_static = pd.read_csv(read_dmc_static_zf.open(zipfile.ZipFile.namelist(read_dmc_static_zf)[0]),
                                  skiprows=9, skipfooter=1, engine='python', encoding="utf-8")
    print(read_dmc_static.shape)
    (114421, 8)

    merge_df = pd.merge(read_dmc_static, read_advertiser_mapping, 
    on='Advertiser')
   print(merge_df.shape)
   110944

    writer_file = pd.ExcelWriter("file.xlsx", engine="xlsxwriter", datetime_format="YYYY-MM-DD")

    x = merge_df.to_excel(writer_file)
    writer_file.save()
    writer_file.close()

文件 Advertiser Marketing 具有37行和 DMC_Static_Conversions 114421行，合并后应返回114303行，但仅 返回110944。

能否请您帮我知道我可以在哪里放置数据？