How to loop over grouped Pandas dataframe

Question

DataFrame     c os family ss c os major is l customer id i 0      Windows 7                         90418 1      Windows 7                         90418 2      Windows 7                         90418   Code   print df for name  group in df groupby  l customer id i   agg lambda x      join x        print name     print group   I m trying to just loop over the aggregated data  but I get the error      ValueError  too many values to unpack    EdChum  here s the expected output                                                       c os family ss    l customer id i 131572           Windows 7 Windows 7 Windows 7 Windows 7 Window    135467           Windows 7 Windows 7 Windows 7 Windows 7 Window                                                          c os major is l customer id i 131572                                                             135467                                                               The output is not the problem  I wish to loop over every group

User · Answer

Here is an example of iterating over a pd DataFrame grouped by the column atable  For this sample   quot create quot  statements for an SQL database are generated within the for loop  import pandas as pd  df1   pd DataFrame        atable         Users    Users    Domains    Domains    Locks         column         col 1    col 2    col a    col b    col         column type    varchar    varchar    int    varchar    varchar         is null        No    No    Yes    No    Yes        df1 grouped   df1 groupby  atable      iterate over each group for group name  df group in df1 grouped      print   nCREATE TABLE      format group name        for row index  row in df group iterrows            col   row  column           column type   row  column type           is null    NOT NULL  if row  is null       NO  else            print   t           format col  column type  is null        print  quot    quot

User · Answer

df groupby  l customer id i   agg lambda x      join x   does already return a dataframe  so you cannot loop over the groups anymore   In general    df groupby      returns a GroupBy object  a DataFrameGroupBy or SeriesGroupBy   and with this  you can iterate through the groups  as explained in the docs here   You can do something like   grouped   df groupby  A    for name  group in grouped           When you apply a function on the groupby  in your example df groupby      agg       but this can also be transform  apply  mean        you combine the result of applying the function to the different groups together in one dataframe  the apply and combine step of the  split-apply-combine  paradigm of groupby   So the result of this will always be again a DataFrame  or a Series depending on the applied function

User · Answer

You can iterate over the index values if your dataframe has already been created   df   df groupby  l customer id i   agg lambda x      join x   for name in df index      print name     print df loc name

[python] How to loop over grouped Pandas dataframe?

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