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

Posted by Matthew Byrne
Matthew Byrne
1,920 Points

sets.py

I can't see what's wrong here. Any suggestions?

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(strings):
    listy = []
    for course in COURSES.keys():
        if strings in course:
            listy.append(course)
    return listy
Cheo R
Cheo R
37,150 Points
Cheo R
Cheo R
37,150 Points

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"].

Looks like in you example, you're checking if the contents of strings is founds in your COURSES.keys().

for course in COURSES.keys():  # ['Python Basics', 'Java Basics', 'PHP Basics', 'Ruby Basics']
        if strings in course:

If the value I pass in were to be, 'taco', listy would return an empty list. If the value I pass n were to be, 'Python', 'listy', would return a list with one item, ['Python Basics'].

But that's not what the question is asking. The question is asking to return a list of course name(s) if the contents of strings is founds in any of the sets for each course. So strings, might not be a string, but say, a list/set. Compare everything in that list/set with the sets for each course, and if there's items that overlap, add that course name to listy.

So you'd want to get something like 

covers(Sets['Python'])

> ["Python Basics"]

covers(Sets(['strings', integers', 'HTML'])

> ["PHP Basics"]

covers(Sets(['strings', 'integers', 'exceptions'])

> ["Java Basics", "Python Basics"]

1 Answer

Kirsten Smith
Kirsten Smith
3,484 Points
Kirsten Smith
Kirsten Smith
3,484 Points

Since you are using sets, it would be easier to compare the lists of courses if you used set math, aka an INTERSECTION to perform the check rather than if __ in ____.