Please check error message about "sort_values"

Question

This Question was resolved. There was an invisible space in "Env"("Env "). Below codes were correct.

Question :

I don't understand error messages about sort_values. Below is printed dataframe.

 print(df)
                                          Value1  Value2  Value3  Value4
     Function Type       Name                                           
     Env      condition   Board             BD#1    BD#2    BD#3    BD#4
                          Temp             High     Room    Low    High 
                          Volt              High     Low     Typ    High
                          SIDD               200      85     185     200
                          Freq             1600M   1600M   1600M   1600M
     CBT      status      CBT_CH0             00      00      00      00
              Input       Data0_CH0           0B      0A      0B      0A
                          Data1_CH0           0C      0C      0D      0B
                          Data2_CH0           07      08      09      06
                          Data3_CH0           06      05      04      08
                          Data4_CH0           01      01      01      03
                          Data5_CH0           00      01      01      02
              Output      Data0_CH0_out       0B      0A      0B      0A
                          Data1_CH0_out       0C      0C      0A      0B
                          Data2_CH0_out       07      04      05      06
                          Data3_CH0_out       06      08      09      05
                          Data4_CH0_out       01      03      04      02
                          Data5_CH0_out       00      02      03      01
              status      CBT_CH1             00      01      02      01
              Input       Data0_CH1           0B      0C      0D      0A
                          Data1_CH1           0C      0B      0A      0D
                          Data2_CH1           07      06      05      08
                          Data3_CH1           06      07      06      07
                          Data4_CH1           01      02      03      02
                          Data5_CH1           00      00      01      01
              Output      Data0_CH1_out       0B      0A      0B      0C
                          Data1_CH1_out       0C      0B      0C      0B
                          Data2_CH1_out       07      07      08      06
                          Data3_CH1_out       06      04      05      04
                          Data4_CH1_out       01      02      03      02
                          Data5_CH1_out       00      01      02      01

I used sort_values to sort column by index in alphabetical order.

  df= df.sort_values(by=('Env','condition','Temp'), axis=1)

But, error message is occurred.

I think the index list('Env','condition','Temp') was correct.

I don't understand below error messages and why that is occurred.

Please, let me know the meaning of below messages.

     ---------------------------------------------------------------------------
     KeyError                                  Traceback (most recent call last)
     <ipython-input-57-1a4fbe80928c> in <module>()
     ----> 1 df= df.sort_values(by=('Env','condition','Temp'), axis=1)

     C:\Users\13ZD970\Anaconda3\lib\site-packages\pandas\core\frame.py in sort_values(self, by, axis, ascending, inplace, kind, na_position)
        4419             by = by[0]
        4420             k = self._get_label_or_level_values(by, axis=axis,
     -> 4421                                                 stacklevel=stacklevel)
        4422 
        4423             if isinstance(ascending, (tuple, list)):

     C:\Users\13ZD970\Anaconda3\lib\site-packages\pandas\core\generic.py in _get_label_or_level_values(self, key, axis, stacklevel)
        1380             values = self.axes[axis].get_level_values(key)._values
        1381         else:
     -> 1382             raise KeyError(key)
        1383 
        1384         # Check for duplicates

     KeyError: ('Env', 'condition', 'Temp')

Try df= df.sort_values(by=['Env','condition','Temp']), note that your error stack trace looks different to your posted code. if you transpose the df then the columns become the index so you then need to pass axis=1 — EdChum
– EdChum, Commented Jan 29, 2019 at 8:42
Sorry, I posted wrong argument. even though I used df= df.sort_values(('Env','condition','Temp', axis=1)), above error messages are occured. — JY Kim
– JY Kim, Commented Jan 29, 2019 at 8:45
I modified it according to your advice. the contents of error messages was changed. — JY Kim
– JY Kim, Commented Jan 29, 2019 at 8:48
Actually don't you want df.sort_values(by=['Function', 'Type','Name'], axis=1) What you passed was the top level values in your multi-index — EdChum
– EdChum, Commented Jan 29, 2019 at 8:49
I changed bigger dataframe. new error messages was generated — JY Kim
– JY Kim, Commented Jan 29, 2019 at 9:03

taurus05 · Accepted Answer · 2019-01-29 10:47:13Z

2

The only thing that you've to change is:

df= df.sort_values(by=['Env','condition','Temp'], axis=1)

The by parameter takes either a string value or a list of string values. Not a tuple, (as you did).

answered Jan 29, 2019 at 10:47

taurus05

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