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:
>>> l = ['a', 'b', 'c']
>>> set(['a', 'b']) <= set(l)
True
>>> set(['a', 'x']) <= set(l)
False
Other solution would be this:
>>> l = ['a', 'b', 'c']
>>> all(x in l for x in ['a', 'b'])
True
>>> all(x in l for x in ['a', 'x'])
False
But here you must do more typing.
Is there any other solutions?
Operators like <=
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'])