TypeError：不可散列的类型：'set'/'list'

Question

I am fairly new to programming and recently started working with dictionaries and a problem I am trying asks for me to create a list of names to take a poll. 2 names must not be in the dictionary while 2 more are in it. The code:

favorite_languages = {
    'jen': 'python',
    'sarah': 'c',
    'edward': 'ruby',
    'phil':  'python'
}
people = {'ryker', 'trey', 'jen', 'edward'}
for keys in favorite_languages:
    if people in favorite_languages:
        print(f"Thanks for taking our poll {people}")

Answer 1

To check if element exists in some List you use in operator, elem in list

print("1" in ["1", "2"]) # prints True

However elem need to be something [hashable][1]. For sure it cannot be set, but look here:

for keys in favorite_languages:
    if people in favorite_languages: # your elem = poeple (which is set)
        print(f"Thanks for taking our poll {people}")

You cannot check all people such way, you should check person one by one, so it would look that way

for person in people: # we iterate over all peoples one by one
    if person in favorite_languages:
        print(f"Thanks for taking our poll {person}")


  [1]: https://stackoverflow.com/questions/14535730/what-does-hashable-mean-in-python

Answer 2

In this solution, I added the names common to both arrays to a list named poll_takers. This way, you only get those names printed in the end.

favorite_languages = {
    'jen': 'python',
    'sarah': 'c',
    'edward': 'ruby',
    'phil':  'python'
}
people = {'ryker', 'trey', 'jen', 'edward'}
poll_takers = []

for p in people:
    for keys in favorite_languages:
        if p in keys:
            poll_takers.append(p)
            print((f"Thanks for taking our poll {' '.join(poll_takers)}."))