Fix Python – How to check if all of the following items are in a list?

Question

Asked By – sirex

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?

Now we will see solution for issue: How to check if all of the following items are in a list?


Answer

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'])

This question is answered By – Glenn Maynard

This answer is collected from stackoverflow and reviewed by FixPython community admins, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0