How to find number of shared elements in a list of sets? python-CodePudding

For example:

fav_tv = [{'The Simpsons', 'Modern Family'}, {'Friends', 'The Simpsons'}, {'The 
      Simpsons', 'Friends', 'Seinfeld'}, {'The Simpsons', 'Seinfeld'}]

output = 1

because 'The Simpsons' is the only show that appears in all sets

CodePudding user response：

Just use the intersection:

len(fav_tv[0].intersection(*fav_tv[1:]))

CodePudding user response：

You can have that with a simple oneliner:

print(len(fav_tv[0].intersection(fav_tv[1], fav_tv[2], fav_tv[3])))

CodePudding user response：

with naive approach

>>> from collections import defaultdict as dd
>>> result = dd(int)
>>> 
>>> fav_tv = [{'The Simpsons', 'Modern Family'}, {'Friends', 'The Simpsons'}, {'The Simpsons', 'Friends', 'Seinfeld'}, {'The Simpsons', 'Seinfeld'}]
>>> 
>>> for i in fav_tv:
...     for j in i:
...             result[j] =1
... 
>>> 
>>> 
>>> result
defaultdict(<class 'int'>, {'Modern Family': 1, 'The Simpsons': 4, 'Friends': 2, 'Seinfeld': 2})
>>> 
>>> 
>>> sum(1 for k, v in result.items() if v==len(fav_tv))
1