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

nakalkucing
nakalkucing
12,964 Points
Posted by nakalkucing
nakalkucing
12,964 Points

I'm having trouble with Challenge Task 1. My code almost works. Help. please!

Here are the instructions: 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 ran my function in Workspaces and got back a list of strings. So I would enter {Python} and get back ['P', 'y', 't', 'h', 'o', 'n', ' ', 'B', 'a', 's', 'i', 'c', 's'] I know I'm missing something obvious but I just cant seem to figure this out. Thanks for your time in advance. : )

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"}
}

course_set = {"Python", "Java", "PHP", "Ruby"}

def covers(course_set):
    for key, value in COURSES.items():
        if course_set.intersection(value):
            return(list(key))
covers(course_set)

1 Answer

Flore W
Flore W
4,744 Points
Flore W
Flore W
4,744 Points

Hi! There are two issues with your code:

1) Use of 'list'

list breaks down an iterable into the elements that compose it. Example:

string = 'apple'
list(string)
> ['a','p','p','l','e']

So removing list in your code will give:

course_set = {"Python", "Java", "PHP", "Ruby"}

def covers(course_set):
    for key, value in COURSES.items():
        if course_set.intersection(value):
            return key
covers(course_set)

> 'Java Basics'

2) Use of "return"

The reason it only returns Java Basics and not the others is because 'return' breaks the loop, so as soon as it returns the first item, then the loop is broken. You need to create a list, and then return the list.

Try this:

def covers(course_set):
    key_list = []
    for key, value in COURSES.items():
        if course_set.intersection(value):
            key_list.append(key)
    return key_list

> ['Java Basics', 'PHP Basics', 'Python Basics', 'PHP Basics']

Hope it helps!

nakalkucing
nakalkucing
12,964 Points
nakalkucing
nakalkucing
12,964 Points

Thanks! I have a hard time with python. I really appreciate your time. :) All the best, Nakal