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Python Python Collections (2016, retired 2019) Sets Set Math

Brian Wang
Brian Wang
2,685 Points
Posted by Brian Wang
Brian Wang
2,685 Points

Help with the second code challenge..

why is my code not working?

sets.py 
COURSES = {
    "Python Basics": {"Python", "functions", "variables",
                      "booleans", "integers", "floats",
                      "arrays", "strings", "exceptions",
                      "conditions", "input", "loops"},
    "Java Basics": {"Java", "strings", "variables",
                    "input", "exceptions", "integers",
                    "booleans", "loops"},
    "PHP Basics": {"PHP", "variables", "conditions",
                   "integers", "floats", "strings",
                   "booleans", "HTML"},
    "Ruby Basics": {"Ruby", "strings", "floats",
                    "integers", "conditions",
                    "functions", "input"}
}

def covers(a_set_of_topic):
    a_list_of_courses = []
    for course in COURSES:
        if a_set_of_topic.intersection(COURSES[course]):
            a_list_of_courses.append(course)
    return a_list_of_courses

def covers_all(a_single_set):
    a_list_of_courses = []
    for course, topic in COURSES.items():
        if a_single_set.intersection(COURSES[topic]):
            a_list_of_courses.append(course)
    return a_list_of_courses

1 Answer

Chris Freeman
MOD
Chris Freeman
Treehouse Moderator 68,441 Points
Chris Freeman
Chris Freeman
Treehouse Moderator 68,441 Points

The Task 2 "Bummer" is coming from the code COURSES[topic]. The key topic is assigned by the for loop to be list of topics covered by a course. It is a set. In the context of your code, you should use the set topic directly.

Fixing this gets passed the Bummer, but yields the wrong results. Name, a course is being added to the a_list_of_courses if there is any common topic between the sets. This is not sufficient. All of the topics in topic have to be present in the course.

Hint: how would the length of the intersection compare to the length of topic if all topics were covered?

Post back if you need more help. Good Luck!!!