pandas merge columns to create new column with comma separated values












3















My dataframe has four columns with colors. I want to combine them into one column called "Colors" and use commas to separate the values.



For example, I'm trying to combine into a Colors column like this :



ID  Black Red  Blue  Green  Colors   
120 NaN red NaN green red, green
121 black Nan blue NaN black, blue


My code is:



df['Colors'] = df[['Black, 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x), axis=1)


But the output for ID 120 is:
, red, , green



And the output for ID 121 is:
black, , blue,



FOUND MY PROBLEM!
Earlier in my code, I replaced "None" with " " instead of NaN. Upon making the change, plus incorporating feedback to insert [x.notnull()], it works!



df['Black'].replace('None', np.nan, inplace=True)
df['Colors'] = df[['Black, 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis=1)









share|improve this question





























    3















    My dataframe has four columns with colors. I want to combine them into one column called "Colors" and use commas to separate the values.



    For example, I'm trying to combine into a Colors column like this :



    ID  Black Red  Blue  Green  Colors   
    120 NaN red NaN green red, green
    121 black Nan blue NaN black, blue


    My code is:



    df['Colors'] = df[['Black, 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x), axis=1)


    But the output for ID 120 is:
    , red, , green



    And the output for ID 121 is:
    black, , blue,



    FOUND MY PROBLEM!
    Earlier in my code, I replaced "None" with " " instead of NaN. Upon making the change, plus incorporating feedback to insert [x.notnull()], it works!



    df['Black'].replace('None', np.nan, inplace=True)
    df['Colors'] = df[['Black, 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis=1)









    share|improve this question



























      3












      3








      3








      My dataframe has four columns with colors. I want to combine them into one column called "Colors" and use commas to separate the values.



      For example, I'm trying to combine into a Colors column like this :



      ID  Black Red  Blue  Green  Colors   
      120 NaN red NaN green red, green
      121 black Nan blue NaN black, blue


      My code is:



      df['Colors'] = df[['Black, 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x), axis=1)


      But the output for ID 120 is:
      , red, , green



      And the output for ID 121 is:
      black, , blue,



      FOUND MY PROBLEM!
      Earlier in my code, I replaced "None" with " " instead of NaN. Upon making the change, plus incorporating feedback to insert [x.notnull()], it works!



      df['Black'].replace('None', np.nan, inplace=True)
      df['Colors'] = df[['Black, 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis=1)









      share|improve this question
















      My dataframe has four columns with colors. I want to combine them into one column called "Colors" and use commas to separate the values.



      For example, I'm trying to combine into a Colors column like this :



      ID  Black Red  Blue  Green  Colors   
      120 NaN red NaN green red, green
      121 black Nan blue NaN black, blue


      My code is:



      df['Colors'] = df[['Black, 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x), axis=1)


      But the output for ID 120 is:
      , red, , green



      And the output for ID 121 is:
      black, , blue,



      FOUND MY PROBLEM!
      Earlier in my code, I replaced "None" with " " instead of NaN. Upon making the change, plus incorporating feedback to insert [x.notnull()], it works!



      df['Black'].replace('None', np.nan, inplace=True)
      df['Colors'] = df[['Black, 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis=1)






      python pandas merge multiple-columns comma






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Jan 2 at 1:43







      KRDavis

















      asked Jan 1 at 21:35









      KRDavisKRDavis

      204




      204
























          2 Answers
          2






          active

          oldest

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          1














          You just need to handle NaNs



          df['Colors'] = df[['Black', 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis = 1)

          ID Black Red Blue Green Colors
          0 120 NaN red NaN green red, green
          1 121 black NaN blue NaN black, blue





          share|improve this answer
























          • Happy new year ~ :-)

            – Wen-Ben
            Jan 1 at 22:04











          • @W-B, wish you a very happy new year :)

            – Vaishali
            Jan 2 at 4:31



















          1














          Using dot



          s=df.iloc[:,1:]
          s.notnull()
          Black Red Blue Green
          0 False True False True
          1 True True True False
          s.notnull().dot(s.columns+',').str[:-1]
          0 Red,Green
          1 Black,Red,Blue
          dtype: object

          df['color']=s.notnull().dot(s.columns+',').str[:-1]





          share|improve this answer























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            2 Answers
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            active

            oldest

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            2 Answers
            2






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            1














            You just need to handle NaNs



            df['Colors'] = df[['Black', 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis = 1)

            ID Black Red Blue Green Colors
            0 120 NaN red NaN green red, green
            1 121 black NaN blue NaN black, blue





            share|improve this answer
























            • Happy new year ~ :-)

              – Wen-Ben
              Jan 1 at 22:04











            • @W-B, wish you a very happy new year :)

              – Vaishali
              Jan 2 at 4:31
















            1














            You just need to handle NaNs



            df['Colors'] = df[['Black', 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis = 1)

            ID Black Red Blue Green Colors
            0 120 NaN red NaN green red, green
            1 121 black NaN blue NaN black, blue





            share|improve this answer
























            • Happy new year ~ :-)

              – Wen-Ben
              Jan 1 at 22:04











            • @W-B, wish you a very happy new year :)

              – Vaishali
              Jan 2 at 4:31














            1












            1








            1







            You just need to handle NaNs



            df['Colors'] = df[['Black', 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis = 1)

            ID Black Red Blue Green Colors
            0 120 NaN red NaN green red, green
            1 121 black NaN blue NaN black, blue





            share|improve this answer













            You just need to handle NaNs



            df['Colors'] = df[['Black', 'Red', 'Blue', 'Green']].apply(lambda x: ', '.join(x[x.notnull()]), axis = 1)

            ID Black Red Blue Green Colors
            0 120 NaN red NaN green red, green
            1 121 black NaN blue NaN black, blue






            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered Jan 1 at 21:40









            VaishaliVaishali

            21.4k41335




            21.4k41335













            • Happy new year ~ :-)

              – Wen-Ben
              Jan 1 at 22:04











            • @W-B, wish you a very happy new year :)

              – Vaishali
              Jan 2 at 4:31



















            • Happy new year ~ :-)

              – Wen-Ben
              Jan 1 at 22:04











            • @W-B, wish you a very happy new year :)

              – Vaishali
              Jan 2 at 4:31

















            Happy new year ~ :-)

            – Wen-Ben
            Jan 1 at 22:04





            Happy new year ~ :-)

            – Wen-Ben
            Jan 1 at 22:04













            @W-B, wish you a very happy new year :)

            – Vaishali
            Jan 2 at 4:31





            @W-B, wish you a very happy new year :)

            – Vaishali
            Jan 2 at 4:31













            1














            Using dot



            s=df.iloc[:,1:]
            s.notnull()
            Black Red Blue Green
            0 False True False True
            1 True True True False
            s.notnull().dot(s.columns+',').str[:-1]
            0 Red,Green
            1 Black,Red,Blue
            dtype: object

            df['color']=s.notnull().dot(s.columns+',').str[:-1]





            share|improve this answer




























              1














              Using dot



              s=df.iloc[:,1:]
              s.notnull()
              Black Red Blue Green
              0 False True False True
              1 True True True False
              s.notnull().dot(s.columns+',').str[:-1]
              0 Red,Green
              1 Black,Red,Blue
              dtype: object

              df['color']=s.notnull().dot(s.columns+',').str[:-1]





              share|improve this answer


























                1












                1








                1







                Using dot



                s=df.iloc[:,1:]
                s.notnull()
                Black Red Blue Green
                0 False True False True
                1 True True True False
                s.notnull().dot(s.columns+',').str[:-1]
                0 Red,Green
                1 Black,Red,Blue
                dtype: object

                df['color']=s.notnull().dot(s.columns+',').str[:-1]





                share|improve this answer













                Using dot



                s=df.iloc[:,1:]
                s.notnull()
                Black Red Blue Green
                0 False True False True
                1 True True True False
                s.notnull().dot(s.columns+',').str[:-1]
                0 Red,Green
                1 Black,Red,Blue
                dtype: object

                df['color']=s.notnull().dot(s.columns+',').str[:-1]






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Jan 1 at 22:04









                Wen-BenWen-Ben

                113k83368




                113k83368






























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