将数据框分组并根据条件在其中选择一个单元格

Question

我的数据集看起来像这样Tr, Date, Time AV81312,20161014,121000 AV81312,20161014,160221 AV85012,20170422,150858 AV85012,20161108,11137 AV86157,20170426,45747 AV86157,20170426,45744 AV86157,20160813,134312

我只需要从每个具有最新记录的Tr中选择一个项目，即具有更高日期和时间的最新记录

所需的输出是Tr, Date, Time AV81312,20161014,160221 AV85012,20170422,150858 AV86157,20170426,45747

我的代码是

df2 = read_csv("sample.csv") df2 = df2.values x = [] for i in df2: for j in df2: if i[2] == j[2]: if i[3] >= j[3]: x.append(i)它没有按预期工作

Answer 1

用 -

df['Date_Time'] = pd.to_datetime(df['Date'].astype(str).str.cat(df['Time'].astype(str)),format='%Y%m%d%H%M%S')
df.loc[df.groupby('Tr')['Date_Time'].idxmax()].drop('Date_Time', axis=1)

输出

        Tr      Date    Time
0  AV81312  20161014  160221
1  AV85012  20170422  150858
2  AV86157  20170426   45747