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  • Redistribute string entries in a huge pandas data frame in Pyhon

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    I have a data frame (derived from a CSV file) with about 100M entries that looks like this:

      df1:
     
          var1   var2
      0     1    2
      1     2    1
      2     1 {3,4,5}
      3     5    6
      4 {4,5,6,7}    8

    I need to convert this into a new data frame in which  (for every row) each element in the braces needs to be associated with the element in the other column, i.e.,

      df2:
     
       var1 var2
      0  1  2
      1  2  1
      2  1  3
      3  1  4
      4  1  5
      5  5  6
      6  4  8
      7  5  8
      8  6  8
      9  7  8

    Each element is a string, even the brace entry itself. Note that the brace element can be in either column, which is different from this: [https://stackoverflow.com/questions/12680754/split-pandas-dataframe-string-entry-to-separate-rows?rq=1][1]. Does anyone know how can I achieve this efficiently for a dataset of about 100M entries? Thanks in advance. 

    Python example:

     

      import pandas as pd
    
      df1 = pd.DataFrame([{'var1': '1', 'var2': '2'},
             {'var1': '2', 'var2': '1'},
             {'var1': '1', 'var2': '{3,4,5}'},
             {'var1': '5', 'var2': '6'},
             {'var1': '{4,5,6,7}', 'var2': '8'}])
     
     
      df2 = pd.DataFrame([{'var1': '1', 'var2': '2'},
             {'var1': '2', 'var2': '1'},
             {'var1': '1', 'var2': '3'},
             {'var1': '1', 'var2': '4'},
             {'var1': '1', 'var2': '5'},
             {'var1': '5', 'var2': '6'},
             {'var1': '4', 'var2': '8'},
             {'var1': '5', 'var2': '8'},
             {'var1': '6', 'var2': '8'},
             {'var1': '7', 'var2': '8'}])

     

 0 Answer(s)

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