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Python

Posted by Nat Rogers
Nat Rogers
7,433 Points

teachers.py help, not sure why this isn't returning a list

def courses(dictionary):
    return list(dictionary.values())

courses is supposed to take a dictionary and return a list of all possible values from the dictionary. I've tried this code in a shell and it appears to work. The error message the treehouse assignment is giving says: Did you return a list of lists? I need just a single list.

Any and all help appreciated. Thanks!

1 Answer

andren
andren
28,558 Points
andren
andren
28,558 Points

As the error message states, your code will return a list of lists, not a list that contains just the courses as strings.

With the example dictionary shown in the challenge your function would return:

[['jQuery Basics', 'Node.js Basics'], ['Python Basics', 'Python Collections']] # list with 2 lists

When the value it is supposed to return is this:

['jQuery Basics', 'Node.js Basics', 'Python Basics', 'Python Collections'] # list with 4 strings

In order to get a flat list like that you have to loop through dictionary.values() and add the contents of the lists it returns to a list that you return.

Like this:

def courses(dictionary):
    all_courses = []
    for course_list in dictionary.values():
      all_courses += course_list
    return all_courses