AND OR in Python

Question

I know that the and and or expressions exist in python  but is there any and or expression  Or some way to combine them in order to produce the same effect as a and or expression   my code looks something like this   if input   a               if  a  or      or      or      or      in someList                      someList remove  a   or someList remove       or someList remove       or someList remove       or someList remove         with this  I mean that if the user inputs  a  and any type of  a  is included in a previously defined list  can I have all the types of  a  removed from a given list   python tells me that there is a problem in   someList remove  a   or someList remove       or someList remove       or someList remove       or someList remove         he tells me  ValueError  list remove x   x not in list

User · Answer

Are you looking for     a if b else c   Or perhaps you misunderstand Python s or  True or True is True

User · Answer

As Matt Ball s answer explains  or is  and or   But or doesn t work with in the way you use it above  You have to say if  a  in someList or      in someList or     Or better yet    if any c in someList for c in   a                                       That s the answer to your question as asked    Other Notes  However  there are a few more things to say about the example code you ve posted  First  the chain of someList remove    or someList remove    statements here is unnecessary  and may result in unexpected behavior  It s also hard to read  Better to break it into individual lines   someList remove  a   someList remove             Even that s not enough  however  As you observed  if the item isn t in the list  then an error is thrown  On top of that  using remove is very slow  because every time you call it  Python has to look at every item in the list  So if you want to remove 10 different characters  and you have a list that has 100 characters  you have to perform 1000 tests   Instead  I would suggest a very different approach  Filter the list using a set  like so   chars to remove   set   a                            someList    c for c in someList if c not in chars to remove    Or  change the list in-place without creating a copy   someList       c for c in someList if c not in chars to remove    These both use list comprehension syntax to create a new list  They look at every character in someList  check to see of the character is in chars to remove  and if it is not  they include the character in the new list   This is the most efficient version of this code  It has two speed advantages     It only passes through someList once  Instead of performing 1000 tests  in the above scenario  it performs only 100   It can test all characters with a single operation  because chars to remove is a set  If it chars to remove were a list or tuple  then each test would really be 10 tests in the above scenario -- because each character in the list would need to be checked individually

User · Answer

For the updated question  you can replace what you want with something like   someList   filter lambda x  x not in   a                            someList    filter evaluates every element of the list by passing it to the lambda provided  In this lambda we check if the element is not one of the characters provided  because these should stay in the list   Alternatively  if the items in someList should be unique  you can make someList a set and do something like this   someList   list set someList -set   a                               This essentially takes the difference between the sets  which does what you want  but also makes sure every element occurs only once  which is different from a list  Note you could store someList as a set from the beginning in this case  it will optimize things a bit

User · Answer

Try this solution   for m in   a                                try          somelist remove m      except          pass   Just for your information  and and or operators are also using to return values  It is useful when you need to assign value to variable but you have some pre-requirements   operator or returns first not null value   init values a b c d    1 2 3 None   print d or a or b or c   output value of a - 1  print b or a or c or d   output value of b - 2   Operator and returns last value in the sequence if any of the members don t have None value or if they have at least one None value we get None  print a and d and b and c   output  None  print a or b or c   output value of c - 3

User · Answer

if input     a       for char in  abc           if char in some list              some list remove char

User · Answer

x and y returns true if both x and y are true  x or y returns if either one is true   From this we can conclude that or contains and within itself unless you mean xOR  or except if and is true

User · Answer

or is not exclusive  e g  xor  so or is the same thing as and or

[python] AND/OR in Python?

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