TypeError unsupported operand type s for - list and list

Question

I am trying to implement the Naive Gauss and getting the unsupported operand type error on execution  Output     execfile filename  namespace    File   media zax MYLINUXLIVE A0N- py   line 26  in  lt module gt      print Naive Gauss   2 3   4 5     6   7      File   media zax MYLINUXLIVE A0N- py   line 20  in Naive Gauss     b row    b row -xmult b column  TypeError  unsupported operand type s  for -   list  and  list   gt  gt  gt       This is the code  def Naive Gauss Array b       n   len Array       for column in xrange n-1           for row in xrange column 1  n               xmult   Array row  column    Array column  column              Array row  column    xmult              print Array row  col              for col in xrange 0  n                   Array row  col    Array row  col  - xmult Array column  col              b row    b row -xmult b column        print Array     print b  print Naive Gauss   2 3   4 5     6   7

User · Answer

The operations needed to be performed  require numpy arrays either created via      np array      or can be converted from list to an array via      np stack     As in the above mentioned case  2 lists are inputted as operands it triggers the error

User · Answer

This question has been answered but I feel I should also mention another potential cause  This is a direct result of coming across the same error message but for different reasons  If your list s are empty the operation will not be performed  check your code for indents and typos

User · Answer

You can t subtract a list from a list    gt  gt  gt   3  7  -  1  2  Traceback  most recent call last     File   lt stdin gt    line 1  in  lt module gt  TypeError  unsupported operand type s  for -   list  and  list    Simple way to do it is using numpy    gt  gt  gt  import numpy as np  gt  gt  gt  np array  3  7   - np array  1  2   array  2  5     You can also use list comprehension  but it will require changing code in the function    gt  gt  gt   a - b for a  b in zip  3  7    1  2     2  5       gt  gt  gt  import numpy as np  gt  gt  gt   gt  gt  gt  def Naive Gauss Array b           n   len Array          for column in xrange n-1               for row in xrange column 1  n                   xmult   Array row  column    Array column  column                  Array row  column    xmult                  print Array row  col                  for col in xrange 0  n                       Array row  col    Array row  col  - xmult Array column  col                  b row    b row -xmult b column          print Array         print b         return Array  b     lt --- Without this  the function will return  None        gt  gt  gt  print Naive Gauss np array   2 3   4 5                           np array   6   7        2  3    -2 -1      6    -5    array    2   3           -2  -1     array    6           -5

User · Answer

Use Set in Python   gt  gt  gt  a    2 4   gt  gt  gt  b    1 4 3   gt  gt  gt  set a  - set b  set  2

[python] TypeError: unsupported operand type(s) for -: 'list' and 'list'

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