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

Don't know how to do the sets challenge...

https://teamtreehouse.com/library/python-collections-2/sets/set-math

Challenge: 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"].

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):
    list_1 = []
    for value in a:
        for courses in COURSES:
            if courses & value:
                list_1.append(courses)
    return list_1
Sam Wederell
Sam Wederell
20,276 Points

You don't need to iterate through the supplied argument 'a'.

Sam Wederell
then why doesnt this work?

def covers(a):
    list_1 = []
    for courses in COURSES:
        if courses & a:
            list_1.append(courses)
    print (list_1)
Sam Wederell
Sam Wederell
20,276 Points

you're comparing the course objects rather than the values.

1 Answer

Steven Parker
Steven Parker
231,275 Points

You're close, in your 2nd try, but there's two issues:

  • you need to test the associated set instead of the key ("if COURSES[courses] & a:")
  • you need to return the new list (and you won't need to "print" anything)