How to rearrange Pandas column sequence

Question

gt  gt  gt  df  DataFrame   a   1 2 3 4   b   2 4 6 8     gt  gt  gt  df  x   df a   df b  gt  gt  gt  df  y   df a - df b  gt  gt  gt  df    a  b   x  y 0  1  2   3 -1 1  2  4   6 -2 2  3  6   9 -3 3  4  8  12 -4   Now I want to rearrange the column sequence  which makes  x   y  column to be the first  amp  second columns by     gt  gt  gt  df   df   x   y   a   b     gt  gt  gt  df     x  y  a  b 0   3 -1  1  2 1   6 -2  2  4 2   9 -3  3  6 3  12 -4  4  8   But if I have a long coulmns  a   b   c   d        and I don t want to explictly list the columns  How can I do that    Or Does Pandas provide a function like set column sequence dataframe col name  seq  so that I can do     set column sequence df  x  0  and set column sequence df  y  1

User · Answer

Feel free to disregard this solution as subtracting a list from an Index does not preserve the order of the original Index  if that s important   In  61   df reindex columns pd Index   x    y    append df columns -   x    y     Out 61        x  y  a  b 0   3 -1  1  2 1   6 -2  2  4 2   9 -3  3  6 3  12 -4  4  8

User · Answer

There may be an elegant built-in function  but I haven t found it yet   You could write one     reorder columns def set column sequence dataframe  seq  front True          Takes a dataframe and a subsequence of its columns         returns dataframe with seq as first columns if  front  is True         and seq as last columns if  front  is False              cols   seq      copy so we don t mutate seq     for x in dataframe columns          if x not in cols              if front   we want  seq  to be in the front                  so append current column to the end of the list                 cols append x              else                   we want  seq  to be last  so insert this                  column in the front of the new column list                   cols  we are building                  cols insert 0  x  return dataframe cols    For your example  set column sequence df    x   y    would return the desired output   If you want the seq at the end of the DataFrame instead simply pass in  front False

User · Answer

def  col seq set df  col list  seq list           set dataframe  df  col list s sequence by seq list         col not in col list    x for x in list df columns  if x not in col list      for i in range len col list            col not in col list insert seq list i   col list i        return df col not in col list  DataFrame col seq set    col seq set

User · Answer

You can do the following   df  DataFrame   a   1 2 3 4   b   2 4 6 8     df  x   df a   df b df  y   df a - df b   create column title whatever order you want in this way   column titles     x   y   a   b    df reindex columns column titles    This will give you desired output

User · Answer

You could also do something like this   df   df   x    y    a    b      You can get the list of columns with   cols   list df columns values    The output will produce something like this     a    b    x    y        which is then easy to rearrange manually before dropping it into the first function

User · Answer

I would suggest you just write a function to do what you re saying probably using drop  to delete columns  and insert to insert columns at a position  There isn t an existing API function to do what you re describing

[python] How to rearrange Pandas column sequence?

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