如何在 python 中使用 pandas 获取所有重复项的列表

问题描述

我有一份可能存在出口问题的物品清单.我想获取重复项目的列表，以便手动比较它们.当我尝试使用 pandas 重复方法时，它只返回第一个复制.有没有办法获取所有重复项，而不仅仅是第一个?

I have a list of items that likely has some export issues. I would like to get a list of the duplicate items so I can manually compare them. When I try to use pandas duplicated method, it only returns the first duplicate. Is there a a way to get all of the duplicates and not just the first one?

我的数据集的一小部分如下所示:

A small subsection of my dataset looks like this:

ID,ENROLLMENT_DATE,TRAINER_MANAGING,TRAINER_OPERATOR,FIRST_VISIT_DATE
1536D,12-Feb-12,"06DA1B3-Lebanon NH",,15-Feb-12
F15D,18-May-12,"06405B2-Lebanon NH",,25-Jul-12
8096,8-Aug-12,"0643D38-Hanover NH","0643D38-Hanover NH",25-Jun-12
A036,1-Apr-12,"06CB8CF-Hanover NH","06CB8CF-Hanover NH",9-Aug-12
8944,19-Feb-12,"06D26AD-Hanover NH",,4-Feb-12
1004E,8-Jun-12,"06388B2-Lebanon NH",,24-Dec-11
11795,3-Jul-12,"0649597-White River VT","0649597-White River VT",30-Mar-12
30D7,11-Nov-12,"06D95A3-Hanover NH","06D95A3-Hanover NH",30-Nov-11
3AE2,21-Feb-12,"06405B2-Lebanon NH",,26-Oct-12
B0FE,17-Feb-12,"06D1B9D-Hartland VT",,16-Feb-12
127A1,11-Dec-11,"064456E-Hanover NH","064456E-Hanover NH",11-Nov-12
161FF,20-Feb-12,"0643D38-Hanover NH","0643D38-Hanover NH",3-Jul-12
A036,30-Nov-11,"063B208-Randolph VT","063B208-Randolph VT",
475B,25-Sep-12,"06D26AD-Hanover NH",,5-Nov-12
151A3,7-Mar-12,"06388B2-Lebanon NH",,16-Nov-12
CA62,3-Jan-12,,,
D31B,18-Dec-11,"06405B2-Lebanon NH",,9-Jan-12
20F5,8-Jul-12,"0669C50-Randolph VT",,3-Feb-12
8096,19-Dec-11,"0649597-White River VT","0649597-White River VT",9-Apr-12
14E48,1-Aug-12,"06D3206-Hanover NH",,
177F8,20-Aug-12,"063B208-Randolph VT","063B208-Randolph VT",5-May-12
553E,11-Oct-12,"06D95A3-Hanover NH","06D95A3-Hanover NH",8-Mar-12
12D5F,18-Jul-12,"0649597-White River VT","0649597-White River VT",2-Nov-12
C6DC,13-Apr-12,"06388B2-Lebanon NH",,
11795,27-Feb-12,"0643D38-Hanover NH","0643D38-Hanover NH",19-Jun-12
17B43,11-Aug-12,,,22-Oct-12
A036,11-Aug-12,"06D3206-Hanover NH",,19-Jun-12

我的代码目前看起来像这样:

My code looks like this currently:

df_bigdata_duplicates = df_bigdata[df_bigdata.duplicated(cols='ID')]

有几个重复的项目.但是，当我使用上面的代码时，我只得到第一项.在 API 参考中，我看到了如何获得最后一项，但我想拥有所有这些，这样我就可以直观地检查它们以了解为什么会出现差异.所以，在这个例子中，我想获取所有三个 A036 条目和 11795 条目以及任何其他重复的条目，而不是第一个.非常感谢任何帮助.

There area a couple duplicate items. But, when I use the above code, I only get the first item. In the API reference, I see how I can get the last item, but I would like to have all of them so I can visually inspect them to see why I am getting the discrepancy. So, in this example I would like to get all three A036 entries and both 11795 entries and any other duplicated entries, instead of the just first one. Any help is most appreciated.

推荐答案

方法#1:打印ID为重复ID之一的所有行:

Method #1: print all rows where the ID is one of the IDs in duplicated:

>>> import pandas as pd
>>> df = pd.read_csv("dup.csv")
>>> ids = df["ID"]
>>> df[ids.isin(ids[ids.duplicated()])].sort("ID")
       ID ENROLLMENT_DATE        TRAINER_MANAGING        TRAINER_OPERATOR FIRST_VISIT_DATE
24  11795       27-Feb-12      0643D38-Hanover NH      0643D38-Hanover NH        19-Jun-12
6   11795        3-Jul-12  0649597-White River VT  0649597-White River VT        30-Mar-12
18   8096       19-Dec-11  0649597-White River VT  0649597-White River VT         9-Apr-12
2    8096        8-Aug-12      0643D38-Hanover NH      0643D38-Hanover NH        25-Jun-12
12   A036       30-Nov-11     063B208-Randolph VT     063B208-Randolph VT              NaN
3    A036        1-Apr-12      06CB8CF-Hanover NH      06CB8CF-Hanover NH         9-Aug-12
26   A036       11-Aug-12      06D3206-Hanover NH                     NaN        19-Jun-12

但我想不出一个很好的方法来防止重复 ids 这么多次.我更喜欢方法 #2:ID 上的 groupby.

but I couldn't think of a nice way to prevent repeating ids so many times. I prefer method #2: groupby on the ID.

>>> pd.concat(g for _, g in df.groupby("ID") if len(g) > 1)
       ID ENROLLMENT_DATE        TRAINER_MANAGING        TRAINER_OPERATOR FIRST_VISIT_DATE
6   11795        3-Jul-12  0649597-White River VT  0649597-White River VT        30-Mar-12
24  11795       27-Feb-12      0643D38-Hanover NH      0643D38-Hanover NH        19-Jun-12
2    8096        8-Aug-12      0643D38-Hanover NH      0643D38-Hanover NH        25-Jun-12
18   8096       19-Dec-11  0649597-White River VT  0649597-White River VT         9-Apr-12
3    A036        1-Apr-12      06CB8CF-Hanover NH      06CB8CF-Hanover NH         9-Aug-12
12   A036       30-Nov-11     063B208-Randolph VT     063B208-Randolph VT              NaN
26   A036       11-Aug-12      06D3206-Hanover NH                     NaN        19-Jun-12

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