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Python

Posted by Gabriel Guerra
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Gabriel Guerra
Data Analysis Techdegree Graduate 9,109 Points

TypeError: unsupported operand type(s) for &: 'set' and 'list'

HI there Any idea why I get this type error:

turkey = {'turkey', 'cheese'}
vegetarian = {'tomato', 'onion', 'mushrooms'}
denver = {'tomato', 'eggs'}
bacon = ['mushrooms', 'eggs']

shared_ingredients = vegetarian & bacon & denver
print(shared_ingredients)

Thanks, Gabriel

1 Answer

Jeff Muday
MOD
Jeff Muday
Treehouse Moderator 28,720 Points
Jeff Muday
Jeff Muday
Treehouse Moderator 28,720 Points

Python is more strict when it comes to sets and operators. These have to be all sets in order to be syntactically correct.

Perhaps you meant this:

turkey = {'turkey', 'cheese'}
vegetarian = {'tomato', 'onion', 'mushrooms'}
denver = {'tomato', 'eggs'}
bacon = {'mushrooms', 'eggs'} # here as a set { }

shared_ingredients = vegetarian & bacon & denver
print(shared_ingredients)

This is also correct:

turkey = {'turkey', 'cheese'}
vegetarian = {'tomato', 'onion', 'mushrooms'}
denver = {'tomato', 'eggs'}
bacon = set( ['mushrooms', 'eggs'] ) # converts the list to a set

shared_ingredients = vegetarian & bacon & denver
print(shared_ingredients)

This will result in the null set because there isn't an intersection of vegetarian, bacon, and denver.