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

Posted by Brandon Galde
Brandon Galde
12,741 Points

I got the right answer, but it is wrong..

Challenge Task 1 of 2

Let's write some functions to explore set math a bit more. We're going to be using this COURSES dict in all of the examples. Don't change it, though! So, first, write a function named covers that accepts a single parameter, a set of topics. Have the function return a list of courses from COURSES where the supplied set and the course's value (also a set) overlap. For example, covers({"Python"}) would return ["Python Basics"].

I have tested my code using python 3.5 and it works just fine. However, when I submit my answer I get "Bummer, Didn't get the right answer from covers". I have no idea what this could be failing on, so any help would be much appreciated.

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(arg):
    val = []
    for course in COURSES:
        if arg.issubset(COURSES[course]):
            val.append(course)
    return val

1 Answer

Umesh Ravji
Umesh Ravji
42,386 Points
Umesh Ravji
Umesh Ravji
42,386 Points

Hi Brandon, while your answer is correct for the given example, it isn't correct if you test with a different set, say {"Python", "Java"}, as you will get no results back (instead of ['Java Basics', 'Python Basics']).

In this question you shouldn't be looking to see if the arg set is a subset of the courses set, but you should be using intersection to see if there is any overlap at all.

If I remember correctly, checking for a subset is the secound task :)

Brandon Galde
Brandon Galde
12,741 Points

Thanks for clarifying that for me, I now understand what is being asked here :P