How to check if all of the following items are in a list

Question

I found  that there is related question  about how to find if at least one item exists in a list  How to check if one of the following items is in a list   But what is the best and pythonic way to find whether all items exists in a list   Searching through the docs I found this solution    gt  gt  gt  l     a    b    c    gt  gt  gt  set   a    b     lt   set l  True  gt  gt  gt  set   a    x     lt   set l  False   Other solution would be this    gt  gt  gt  l     a    b    c    gt  gt  gt  all x in l for x in   a    b    True  gt  gt  gt  all x in l for x in   a    x    False   But here you must do more typing   Is there any other solutions

User · Accepted Answer

Operators like  lt   in Python are generally not overriden to mean something significantly different than  less than or equal to    It s unusual for the standard library does this--it smells like legacy API to me   Use the equivalent and more clearly-named method  set issubset   Note that you don t need to convert the argument to a set  it ll do that for you if needed   set   a    b    issubset   a    b    c

User · Answer

Not OP s case  but - for anyone who wants to assert intersection in dicts  and ended up here due to poor googling  e g  me  - you need to work with dict items    gt  gt  gt  a     key    value    gt  gt  gt  b     key    value    extra key    extra value    gt  gt  gt  all item in a items   for item in b items    True  gt  gt  gt  all item in b items   for item in a items    False   That s because dict items returns tuples of key value pairs  and much like any object in Python  they re interchangeably comparable

User · Answer

What if your lists contain duplicates like this   v1     s    h    e    e    p   v2     s    s    h     Sets do not contain duplicates  So  the following line returns True   set v2  issubset v1    To count for duplicates  you can use the code   v1   sorted v1  v2   sorted v2    def is subseq v2  v1          Check whether v2 is a subsequence of v1         it   iter v1      return all c in it for c in v2     So  the following line returns False   is subseq v2  v1

User · Answer

I like these two because they seem the most logical  the latter being shorter and probably fastest  shown here using set literal syntax which has been  backported to Python 2 7    all x in   a    b    c   for x in   a    b        or   a    b   issubset   a    b    c

User · Answer

This was what I was searching online but unfortunately found not online but while experimenting on python interpreter    gt  gt  gt  case     caseCamel   gt  gt  gt  label    Case Camel   gt  gt  gt  list      apple    banana    gt  gt  gt   gt  gt  gt   case or label  in list False  gt  gt  gt  list     apple    caseCamel    gt  gt  gt   case or label  in list True  gt  gt  gt   case and label  in list False  gt  gt  gt  list     case    caseCamel    Case Camel    gt  gt  gt   case and label  in list True  gt  gt  gt    and if you have a looong list of variables held in a sublist variable   gt  gt  gt   gt  gt  gt  list      case    caseCamel    Case Camel    gt  gt  gt  label    Case Camel   gt  gt  gt  case     caseCamel   gt  gt  gt   gt  gt  gt  sublist     unique banana    very unique banana    gt  gt  gt   gt  gt  gt    example for if any  at least one  item contained in superset  or statement       gt  gt  gt  next  True for item in sublist if next  True for x in list if x    item   False    False  False  gt  gt  gt   gt  gt  gt  sublist 0    label  gt  gt  gt   gt  gt  gt  next  True for item in sublist if next  True for x in list if x    item   False    False  True  gt  gt  gt   gt  gt  gt    example for whether a subset  all items  contained in superset  and statement       gt  gt  gt    a bit of demorgan s law      gt  gt  gt  next  False for item in sublist if item not in list   True  False  gt  gt  gt   gt  gt  gt  sublist 1    case  gt  gt  gt   gt  gt  gt  next  False for item in sublist if item not in list   True  True  gt  gt  gt   gt  gt  gt  next  True for item in sublist if next  True for x in list if x    item   False    False  True  gt  gt  gt   gt  gt  gt

User · Answer

An example of how to do this using a lambda expression would be   issublist   lambda x  y  0 in    in x for   in y

User · Answer

I would probably use set in the following manner     set l  issuperset set   a   b        or the other way round     set   a   b    issubset set l      I find it a bit more readable  but it may be over-kill  Sets are particularly useful to compute union intersection differences between collections  but it may not be the best option in this situation

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