Subtracting 2 lists in Python

Question

Right now I have vector3 values represented as lists  is there a way to subtract 2 of these like vector3 values  like   2 2 2  -  1 1 1     1 1 1    Should I use tuples   If none of them defines these operands on these types  can I define it instead   If not  should I create a new vector3 class

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import numpy as np a    2 2 2  b    1 1 1  np subtract a b

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If you have two lists called  a  and  b   you can do   m - n for m n in zip a b

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If your lists are a and b  you can do   map int   sub    a  b    But you probably shouldn t   No one will know what it means

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Here s an alternative to list comprehensions   Map iterates through the list s   the latter arguments   doing so simulataneously  and passes their elements as arguments to the function  the first arg    It returns the resulting list  import operator map operator sub  a  b   This code because has less syntax  which is more aesthetic for me   and apparently it s 40  faster for lists of length 5  see bobince s comment    Still  either solution will work

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The combination of map and lambda functions in Python is a good solution for this kind of problem   a    2 2 2  b    1 1 1  map lambda x y  x-y  a b    zip function is another good choice  as demonstrated by  UncleZeiv

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For the one who used to code on Pycharm  it also revives others as well    import operator  Arr1  1 2 3 45   Arr2  3 4 56 78   print list map operator sub Arr1 Arr2

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I d have to recommend NumPy as well  Not only is it faster for doing vector math  but it also has a ton of convenience functions   If you want something even faster for 1d vectors  try vop  It s similar to MatLab  but free and stuff   Here s an example of what you d do  from numpy import matrix a   matrix  2 2 2   b   matrix  1 1 1   ret   a - b print ret  gt  gt    1 1 1     Boom

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arr1  1 2 3  arr2  2 1 3  ls  arr2-arr1 for arr1 arr2 in zip arr1 arr2   print ls   gt  gt  1 -1 0

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This answer shows how to write  quot normal easily understandable quot  pythonic code  I suggest not using zip as not really everyone knows about it     The solutions use list comprehensions and common built-in functions   Alternative 1  Recommended   a    2  2  2  b    1  1  1  result    a i  - b i  for i in range len a     Recommended as it only uses the most basic functions in Python  Alternative 2  a    2  2  2  b    1  1  1  result    x - b i  for i  x in enumerate a     Alternative 3  as mentioned by BioCoder   a    2  2  2  b    1  1  1  result   list map lambda x  y  x - y  a  b

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Try this   list array  1 2 3  -1

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If this is something you end up doing frequently  and with different operations  you should probably create a class to handle cases like this  or better use some library like Numpy   Otherwise  look for list comprehensions used with the zip builtin function    a i - b i for a i  b i in zip a  b

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A slightly different Vector class   class Vector  object        def   init   self   data           self data   data     def   repr   self           return repr self data       def   add   self  other           return tuple   a b for a b in zip self data  other data            def   sub   self  other           return tuple   a-b for a b in zip self data  other data       Vector 1  2  3  - Vector 1  1  1

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If you plan on performing more than simple one liners  it would be better to implement your own class and override the appropriate operators as they apply to your case   Taken from Mathematics in Python   class Vector     def   init   self  data       self data   data    def   repr   self       return repr self data       def   add   self  other       data          for j in range len self data          data append self data j    other data j       return Vector data     x   Vector  1  2  3       print x   x

[python] Subtracting 2 lists in Python

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