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

mahdi askari
mahdi askari
15,174 Points

What am I doing wrong?

I am having problem solving the task

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):
    hold = []  
    for key, value in COURSES.items():
        #key is the course names (e.g. Python, Ruby) and value is the sets{'Python', 'functions' etc.} that we want to compare
        if value & arg:
        #so value(set1).intersection(set2) - finds common items between sets
            hold.append(key)
    return hold
covers({'Ruby'})

def covers_all(arg):
    my_list = []
    for key, value in COURSES.items():
        if value & arg:
            my_list.append(key)
    return my_list

1 Answer

Cheo R
Cheo R
37,150 Points

The problem lies with:

#covers_all
if value & arg:

For the test case, covers_all({"conditions", "input"}), it returns true if either arg is found in value. For example:

def covers_all(arg):
    my_list = []
    for key, value in COURSES.items():
        if value & arg:
            my_list.append(key)
    return my_list

print(covers_all({"conditions", "input"}))  # ['Python Basics', 'Java Basics', 'PHP Basics', 'Ruby Basics']

Both Java Basics and PHP Basics have only one of the args present, but not all.

What you need to do: verify all of given args are in value.