how to concatenate lists with data frames within in python

Question

I have two lists, each one with the same number of dataframes that I imported from csv files.

So "dataframes" has 12 dataframes and "Dataframes potential" has also 12 Dataframes.

They have the same number of rows and I would like to concatenate them (pair of each one).

dataframes

    [                       Name  people  ...  Tcs_sys_sup_C  Tcs_sys_re_C
 DATE                                 ...                             
 2011-01-01 00:00:00  B10540    42.0  ...            0.0           0.0
 2011-01-01 01:00:00  B10540    42.0  ...            0.0           0.0
 2011-01-01 02:00:00  B10540    42.0  ...            0.0           0.0
 2011-01-01 03:00:00  B10540    42.0  ...            0.0           0.0
 2011-01-01 04:00:00  B10540    42.0  ...            0.0           0.0
 ...                     ...     ...  ...            ...           ...
 2011-12-31 19:00:00  B10540    41.0  ...            0.0           0.0
 2011-12-31 20:00:00  B10540    41.0  ...            0.0           0.0
 2011-12-31 21:00:00  B10540    42.0  ...            0.0           0.0
 2011-12-31 22:00:00  B10540    42.0  ...            0.0           0.0
 2011-12-31 23:00:00  B10540    42.0  ...            0.0           0.0
 
 [8760 rows x 136 columns],
                        Name  people  ...  Tcs_sys_sup_C  Tcs_sys_re_C
 DATE                                 ...                             
 2011-01-01 00:00:00  B10549     1.0  ...            0.0           0.0
 2011-01-01 01:00:00  B10549     1.0  ...            0.0           0.0
 2011-01-01 02:00:00  B10549     1.0  ...            0.0           0.0
 2011-01-01 03:00:00  B10549     1.0  ...            0.0           0.0
 2011-01-01 04:00:00  B10549     1.0  ...            0.0           0.0
 ...                     ...     ...  ...            ...           ...
 2011-12-31 19:00:00  B10549     1.0  ...            0.0           0.0
 2011-12-31 20:00:00  B10549     1.0  ...            0.0           0.0
 2011-12-31 21:00:00  B10549     1.0  ...            0.0           0.0
 2011-12-31 22:00:00  B10549     1.0  ...            0.0           0.0
 2011-12-31 23:00:00  B10549     1.0  ...            0.0           0.0
 
 [8760 rows x 136 columns],.....

and Dataframes potential

    [                     SC_FP_walls_south_Q_kWh  ...  T_SC_re_C
 Date                                          ...           
 2011-01-01 00:00:00                      0.0  ...        NaN
 2011-01-01 01:00:00                      0.0  ...        NaN
 2011-01-01 02:00:00                      0.0  ...        NaN
 2011-01-01 03:00:00                      0.0  ...        NaN
 2011-01-01 04:00:00                      0.0  ...        NaN
 ...                                      ...  ...        ...
 2011-12-31 19:00:00                      0.0  ...        NaN
 2011-12-31 20:00:00                      0.0  ...        NaN
 2011-12-31 21:00:00                      0.0  ...        NaN
 2011-12-31 22:00:00                      0.0  ...        NaN
 2011-12-31 23:00:00                      0.0  ...        NaN
 
 [8760 rows x 18 columns],
                      SC_FP_walls_south_Q_kWh  ...  T_SC_re_C
 Date                                          ...           
 2011-01-01 00:00:00                      0.0  ...        NaN
 2011-01-01 01:00:00                      0.0  ...        NaN
 2011-01-01 02:00:00                      0.0  ...        NaN
 2011-01-01 03:00:00                      0.0  ...        NaN
 2011-01-01 04:00:00                      0.0  ...        NaN
 ...                                      ...  ...        ...
 2011-12-31 19:00:00                      0.0  ...        NaN
 2011-12-31 20:00:00                      0.0  ...        NaN
 2011-12-31 21:00:00                      0.0  ...        NaN
 2011-12-31 22:00:00                      0.0  ...        NaN
 2011-12-31 23:00:00                      0.0  ...        NaN
 
 [8760 rows x 18 columns],....

I tried a very simple

frames=[dataframes_potencial_process,dataframes] 
pd.concat(frames)
TypeError: cannot concatenate object of type '<class 'list'>'; only Series and DataFrame objs are valid

Thank you

Suppose you have: dfs = [df1, df2, df3], and dfs_potential = [dfp1, dfp2, dfp3]. Its hard to tell from your question whether you want final = df1+df2+df3+dfp1+dfp2+dfp3 (case 1) OR final = [df1+dfp1, df2+dfp2, df3+dfp3] (case 2). If you just want to concat everything (case 1), use final= pd.concat(dfs + dfs_potential, axis =1). For case 2, use [pd.concat([dfs[i], dfs_potential[i]], axis=1) for i in len(dfs)] — Parmandeep Chaddha
– Parmandeep Chaddha, Commented Apr 14, 2021 at 16:54

Andrej Kesely · Accepted Answer · 2021-04-14 16:38:59Z

1

As you stated in the question, you want to concatenate them (pair of each one). You can use zip and pd.concat with axis=1:

pairs = [pd.concat(d, axis=1) for d in zip(dataframes_potencial_process, dataframes)]

# print the pairs:
print(*pairs, sep="\n\n")

answered Apr 14, 2021 at 16:38

Andrej Kesely

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Anurag Dabas · Accepted Answer · 2021-04-14 18:14:34Z

1

Try with concat() method:

dataframes_potencial_process=pd.concat(dataframes_potencial_process,ignore_index=True)
dataframes=pd.concat(dataframes,ignore_index=True)

Finally again use concat() method:

resultdf=pd.concat((dataframes_potencial_process,dataframes),ignore_index=True,axis=1)

Now if you print resultdf you will get your desired output

edited Apr 14, 2021 at 18:14

answered Apr 14, 2021 at 16:35

Anurag Dabas

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