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

Akshaan Mazumdar
Akshaan Mazumdar
3,787 Points
Posted by Akshaan Mazumdar
Akshaan Mazumdar
3,787 Points

ERROR! HELP!! CODE WORKS FINE IN MY EDITOR but NOT IN THE CHALLENGE

I am receiving error message Didn't get the right output from covers

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(subset):
    listx=[]
    for keys,items in COURSES.items():
        if subset&items==subset:
            listx.append(keys)

    return listx

1 Answer

Joey Bruijns
.a{fill-rule:evenodd;}techdegree seal-36
Joey Bruijns
Full Stack JavaScript Techdegree Graduate 47,878 Points

Hi Akshaan,

In your if statement it should be enough to use the set operator intersection (&) because it gives you back exactly what you want!

The result of if subset & value: checks if there are any items that are both in the COURSES dictionary and in the arguments you give to the covers function.

In your statement you asked if the intersection between subset and value is equal to subset. This doesn't give you back all the matching course names.

Hopefully this answers your question!

def covers(subset):
    listx = []
    for keys,value in COURSES.items():
        if subset & value:
            listx.append(keys)
    return listx