Pandas drop columns based on column name AND content












1















I have a dataframe like this:



df = pd.DataFrame([[1,2,np.nan,np.nan,5],[3,4,np.nan,np.nan,6]],columns=['a','b','c','Unnamed: 4','Unnamed: 5'])

df
Out[16]:
a b c Unnamed: 4 Unnamed: 5
0 1 2 NaN NaN 5
1 3 4 NaN NaN 6


I want to drop columns that are BOTH all nan AND have 'Unnamed: ' in the name (as often happens when importing a dataframe from a file with columns that have no name in the header). Desired output:



   a  b   c  Unnamed: 5
0 1 2 NaN 5
1 3 4 NaN 6


I can do:



df[[col for col in df.columns if 'Unnamed: ' not in col]]
Out[18]:
a b c
0 1 2 NaN
1 3 4 NaN


or:



df.dropna(how='all',axis=1)

Out[19]:
a b Unnamed: 5
0 1 2 5
1 3 4 6


Is there a pythonic way to do both these things simultaneously (connected by AND not OR)?










share|improve this question



























    1















    I have a dataframe like this:



    df = pd.DataFrame([[1,2,np.nan,np.nan,5],[3,4,np.nan,np.nan,6]],columns=['a','b','c','Unnamed: 4','Unnamed: 5'])

    df
    Out[16]:
    a b c Unnamed: 4 Unnamed: 5
    0 1 2 NaN NaN 5
    1 3 4 NaN NaN 6


    I want to drop columns that are BOTH all nan AND have 'Unnamed: ' in the name (as often happens when importing a dataframe from a file with columns that have no name in the header). Desired output:



       a  b   c  Unnamed: 5
    0 1 2 NaN 5
    1 3 4 NaN 6


    I can do:



    df[[col for col in df.columns if 'Unnamed: ' not in col]]
    Out[18]:
    a b c
    0 1 2 NaN
    1 3 4 NaN


    or:



    df.dropna(how='all',axis=1)

    Out[19]:
    a b Unnamed: 5
    0 1 2 5
    1 3 4 6


    Is there a pythonic way to do both these things simultaneously (connected by AND not OR)?










    share|improve this question

























      1












      1








      1








      I have a dataframe like this:



      df = pd.DataFrame([[1,2,np.nan,np.nan,5],[3,4,np.nan,np.nan,6]],columns=['a','b','c','Unnamed: 4','Unnamed: 5'])

      df
      Out[16]:
      a b c Unnamed: 4 Unnamed: 5
      0 1 2 NaN NaN 5
      1 3 4 NaN NaN 6


      I want to drop columns that are BOTH all nan AND have 'Unnamed: ' in the name (as often happens when importing a dataframe from a file with columns that have no name in the header). Desired output:



         a  b   c  Unnamed: 5
      0 1 2 NaN 5
      1 3 4 NaN 6


      I can do:



      df[[col for col in df.columns if 'Unnamed: ' not in col]]
      Out[18]:
      a b c
      0 1 2 NaN
      1 3 4 NaN


      or:



      df.dropna(how='all',axis=1)

      Out[19]:
      a b Unnamed: 5
      0 1 2 5
      1 3 4 6


      Is there a pythonic way to do both these things simultaneously (connected by AND not OR)?










      share|improve this question














      I have a dataframe like this:



      df = pd.DataFrame([[1,2,np.nan,np.nan,5],[3,4,np.nan,np.nan,6]],columns=['a','b','c','Unnamed: 4','Unnamed: 5'])

      df
      Out[16]:
      a b c Unnamed: 4 Unnamed: 5
      0 1 2 NaN NaN 5
      1 3 4 NaN NaN 6


      I want to drop columns that are BOTH all nan AND have 'Unnamed: ' in the name (as often happens when importing a dataframe from a file with columns that have no name in the header). Desired output:



         a  b   c  Unnamed: 5
      0 1 2 NaN 5
      1 3 4 NaN 6


      I can do:



      df[[col for col in df.columns if 'Unnamed: ' not in col]]
      Out[18]:
      a b c
      0 1 2 NaN
      1 3 4 NaN


      or:



      df.dropna(how='all',axis=1)

      Out[19]:
      a b Unnamed: 5
      0 1 2 5
      1 3 4 6


      Is there a pythonic way to do both these things simultaneously (connected by AND not OR)?







      python pandas dataframe






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      asked Nov 14 '18 at 23:09









      andbeonetravelerandbeonetraveler

      178213




      178213
























          1 Answer
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          2















          filter + isnull + drop



          First filter your dataframe for column labels, then calculate which are all null:



          nulls = df.filter(like='Unnamed').isnull().all()

          df = df.drop(nulls[nulls].index, axis='columns')

          print(df)

          a b c Unnamed: 5
          0 1 2 NaN 5
          1 3 4 NaN 6





          share|improve this answer























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            1 Answer
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            active

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            2















            filter + isnull + drop



            First filter your dataframe for column labels, then calculate which are all null:



            nulls = df.filter(like='Unnamed').isnull().all()

            df = df.drop(nulls[nulls].index, axis='columns')

            print(df)

            a b c Unnamed: 5
            0 1 2 NaN 5
            1 3 4 NaN 6





            share|improve this answer




























              2















              filter + isnull + drop



              First filter your dataframe for column labels, then calculate which are all null:



              nulls = df.filter(like='Unnamed').isnull().all()

              df = df.drop(nulls[nulls].index, axis='columns')

              print(df)

              a b c Unnamed: 5
              0 1 2 NaN 5
              1 3 4 NaN 6





              share|improve this answer


























                2












                2








                2








                filter + isnull + drop



                First filter your dataframe for column labels, then calculate which are all null:



                nulls = df.filter(like='Unnamed').isnull().all()

                df = df.drop(nulls[nulls].index, axis='columns')

                print(df)

                a b c Unnamed: 5
                0 1 2 NaN 5
                1 3 4 NaN 6





                share|improve this answer














                filter + isnull + drop



                First filter your dataframe for column labels, then calculate which are all null:



                nulls = df.filter(like='Unnamed').isnull().all()

                df = df.drop(nulls[nulls].index, axis='columns')

                print(df)

                a b c Unnamed: 5
                0 1 2 NaN 5
                1 3 4 NaN 6






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered Nov 14 '18 at 23:13









                jppjpp

                101k2163112




                101k2163112
































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