合并具有不同维度和相关数据的数据框 [英] Merging dataframes with different dimensions and related data

问题描述

我有2个大小不同的数据帧，并以有效的方式合并了相关数据:

I have 2 dataframes with different size with related data to be merged in an efficient way:

master_df = pd.DataFrame({'kpi_1': [1,2,3,4]},
                         index=['dn1_app1_bar.com',
                                'dn1_app2_bar.com',
                                'dn2_app1_foo.com', 
                                'dn2_app2_foo.com'])


guard_df = pd.DataFrame({'kpi_2': [1,2],
                         'kpi_3': [10,20]},
                         index=['dn1_bar.com', 'dn2_foo.com'])

master_df:

master_df:

                  kpi_1
dn1_app1_bar.com      1
dn1_app2_bar.com      2
dn2_app1_foo.com      3
dn2_app2_foo.com      4

guard_df:

             kpi_2  kpi_3
dn1_bar.com      1     10
dn2_foo.com      2     20

我想从guard_df的行中获取值，并以<group>_<name>的索引传播"到所有master_df匹配的行中的值 <group>_.*_<name>.

I want to get a dataframe with values from a guard_df's row indexed with <group>_<name> "propagated' to all master_df's rows matching <group>_.*_<name>.

预期结果:

                  kpi_1  kpi_2  kpi_3
dn1_app1_bar.com      1    1.0   10.0
dn1_app2_bar.com      2    1.0   10.0
dn2_app1_foo.com      3    2.0   20.0
dn2_app2_foo.com      4    2.0   20.0

到目前为止，我管理的是以下基本方法:

What I've managed so far is the following basic approach:

def eval_base_dn(dn):
    chunks = dn.split('_')
    return '_'.join((chunks[0], chunks[2]))

for dn in master_df.index:
    for col in guard_df.columns:
        master_df.loc[dn, col] = guard_df.loc[eval_base_dn(dn), col]

但是我正在寻找一种更高性能的方式来广播"值并合并数据帧.

but I'm looking for some more performant way to "broadcast" the values and merge the dataframes.

推荐答案

如果可以使用0.25+熊猫，请通过array，此处将index传递给merge的on参数，并使用左连接:

If use pandas 0.25+ is possible pass array, here index to on parameter of merge with left join:

master_df = master_df.merge(guard_df, 
                            left_on=master_df.index.str.replace('_.+_', '_'), 
                            right_index=True, 
                            how='left')
print (master_df)
                  kpi_1  kpi_2  kpi_3
dn1_app1_bar.com      1      1     10
dn1_app2_bar.com      2      1     10
dn2_app1_foo.com      3      2     20
dn2_app2_foo.com      4      2     20

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