Sets.py code challenge task 1 failing.

I was only able to make this work by casting the values list inside the COURSES dictionary to a set, and then using intersection. This makes this task quite confusing for beginners.

def covers(p):
    ret = []
    for k, v in COURSES.items():
        setv = set(v)
        if p.intersection(setv):
            ret.append(k)
    return ret

I think it should be done in the way sets work in Python. My Code is as follows and it run smoothly

  def covers(topics):
    courses_list = []    
    for course in COURSES:
        if COURSES[course] & topics:   # Here the & sign finds the overlaps of the two sets.
            courses_list.append(course)
    return courses_list

Hey Michael Lutz

I've managed to pass first challange with your code.

The only problem you had in there is redundant check for equality in if condition. Probably, it was also generated strange behaviors.

So I replace:

if value&set2 == set2:

to

if value & set2:

And it should do the trick!

Hi Everyone, I did something similar but in order to use what we just learn I used "intersection". I worked very well.

def covers(arg):
    final = set()
    for key , value in COURSES.items():
        if value.intersection(arg):
            final.update({key})
    return list(final)

Thank you, Andrew! That did the trick - much appreciated!

Hi

I have a different solution that works in my terminal window but I'm also getting the "Bummer!" error message in the challenge interface. Any idea what went wrong with my code?

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(*args):
    set2 = set()
    for arg in args:
        set2.update({arg})
    set1 = set()
    for key, value in COURSES.iteritems():
        if len(set(value)&set2) == len(set2):
            set1.update({key})
    print set1

covers('Ruby','input') 

It looks like you are returning a set rather than a list.

Hi Michael,

for one I notice that you go through a - to my mind - complicated mechanism of having *args as your prameter and then creating a set with each arg from *args. Since you get a set anyhow passed into covers() by the code challenge, that is redundant. You could simply use:

def covers(set2):
    set1 = set()
    # no need to intialize set2
    # the rest of your code

But maybe you were trying it out. I suppose the task should pass anyway.

As for what is actually not working, I am trying to wrap my head around what you are doing with len(). Since you are supposed to check whether set2 is part of set1, I don't understand what you are doing there.

Hi Michael,

glad that was helpful!

Please post your entire current code here. I ran it in workspaces and I get a TypeError: unsupported operand type(s) for &: 'set' and 'tuple'. It refers to the following line of code:

if value&set2 == set2:

In case it helps anyone else, my code originally passed in Workspaces but not on the challenge page because I forgot to change the practice input into a set.

I was inadvertently having the covers function accept a string instead, so I kept getting the same TypeError.

I fixed it this way:

user_topic = input("> ") 
user_set = set(user_topic.split()) 

And then I plugged user_set into the covers function to test it.

print("{}".format(covers(user_set)))

I'm sure there's a more Pythonic way to do this, but it got me through Part 1 of the challenge. (Over an hour later, and only with help from this thread.)

This is the code that ended up working for me:

def covers(topic):
    courses_list = []
    for name, topics in COURSES.items():
        if topic & topics:
            courses_list.append(name)
    return courses_list

Just hoping this helps someone the way you've all helped me. :)