array filter in python

Question

For example  I have two lists     A              6  7  8  9  10  11  12  subset of A     6  9  12     the subset of A   the result should be  7  8  10  11   the remaining elements    Is there a built-in function in python to do this

User · Answer

Use the Set type   A set   Set  6 7 8 9 10 11 12   subset of A set   Set  6 9 12    result   A set - subset of A set

User · Answer

Yes  the filter function   filter lambda x  x not in subset of A  A

User · Answer

tuple set  6  7  8  9  10  11  12   difference  6  9  12

User · Answer

No  there is no build in function in python to do this  because simply     set A - set subset of A    will provide you the answer

User · Answer

gt  gt  gt  A              6  7  8  9  10  11  12   gt  gt  gt  subset of A     6  9  12    gt  gt  gt  set A  - set subset of A  set  8  10  11  7    gt  gt  gt

User · Answer

gt  gt  gt  a   set  6  7  8  9  10  11  12    gt  gt  gt  sub a   set  6  9  12    gt  gt  gt  a - sub a set  8  10  11  7

User · Answer

This was just asked a couple of days ago  but I cannot find it     gt  gt  gt  A    6  7  8  9  10  11  12   gt  gt  gt  subset of A   set  6  9  12    gt  gt  gt   i for i in A if i not in subset of A   7  8  10  11    It might be better to use sets from the beginning  depending on the context  Then you can use set operations like other answers show    However  converting lists to sets and back only for these operations is slower than list comprehension

User · Answer

set A -set subset of A  gives your the intended result set  but it won t retain the original order  The following is order preserving    a for a in A if not a in subset of A

User · Answer

If the order is not important  you should use set difference  However  if you want to retain order  a simple list comprehension is all it takes   result    a for a in A if a not in subset of A    EDIT  As delnan says  performance will be substantially improved if subset of A is an actual set  since checking for membership in a set is O 1  as compared to O n  for a list   A    6  7  8  9  10  11  12  subset of A   set  6  9  12     the subset of A  result    a for a in A if a not in subset of A

User · Answer

How about  set A  difference subset of A

[python] array filter in python?

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