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Andrei Oprescu
9,547 PointsCan someone help me with this challenge?
Hi!
I am doing this challenge which asks me this:
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"].
My code that I used for this challenge is at the bottom of this question.
Can someone tell me what I did wrong?
Thanks!
Andrei
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(topics):
return topics.intersection(COURSES)
6 Answers
Dave StSomeWhere
19,870 PointsHi Andrei,
Two issues I noticed:
-
your statement below returns a set, not a list as per the instructions.
return topics.intersection(COURSES) COURSES is a set of sets, so doing the intersection with COURSES does not return anything. You need to iterate through the sets and sets do not support indexes. I used a for loop, do you know how to loop through COURSES and then return each course including the topic as a list item?
Andrei Oprescu
9,547 PointsHi Dave!
I have followed your instructions and came up with this code:
def covers(topics):
result = []
for key, value in COURSES.items():
if topics.intersection(value) is True:
result.append(key)
return result
I tried to run it in the workspaces and it gave me no result. Can you please suggest what I did wrong this time?
Thanks!
Andrei
Dave StSomeWhere
19,870 PointsIf that is the code you tried in workspaces you would still need to define a function to return a value and I don't see where you are setting the value for topics.
For debugging just try print() to get it worked out. The only issue I see is the "is True" on the if statement - doing just the intersection with result in a True or False result and you can verify you are getting a result with prints (or define the whole thing and do the print on result after.
if topics.intersection(value):
print(key)
print(value)
The loop and append look correct.
Andrei Oprescu
9,547 PointsHi Dave!
I have followed your advice and it was very useful. When I tried this code in the workspace it printed out all of the tracks that had a specific topic in it:
def covers(topics): result = [] for key, value in COURSES.items(): if topics.intersection(value): print(key) return result
although when i tried this code:
def covers(topics): result = [] for key, value in COURSES.items(): if topics.intersection(value): result.append(key) return result
I got no topics.
can you tell me why this might be?
Thanks!
Andrei
Dave StSomeWhere
19,870 PointsAre you sure you are indenting correctly?
When I run your code as per below, it is happy and works properly:
def covers(topics):
result = []
for key, value in COURSES.items():
if topics.intersection(value):
result.append(key)
return result
print(str(covers({"Python"})))
Andrei Oprescu
9,547 PointsHi Dave!
Sorry! It was my mistake since when I tried out my code I just called my function, but did not also print it! :)
Thank you!
Andrei
Tor Ivan Boine
4,057 PointsDave varmutant, I tried your code in IDLE, and it fails
>>> covers('Python')
Traceback (most recent call last):
File "<pyshell#119>", line 1, in <module>
covers('Python')
File "H:\Dropbox\3 Programmering\Python\test.py", line 19, in covers
if topics.intersection(value):
AttributeError: 'str' object has no attribute 'intersection
But it works in the task. how do I run it?
Dave StSomeWhere
19,870 PointsGood deal, more testing = more learning and just for fun, it is your code not mine hehe...
Notice that the error message is that a string doesn't have an intersection attribute.
You need to pass a set because sets have the intersection attribute. Notice that how I run the function is with the following statement - passing a set not a string:
print(str(covers({"Python"})))
Tor Ivan Boine
4,057 Pointsaha, that makes somewhat sense. Thanks. Wish these tasks (in general) were more informative. I don't have a photographic memory (if such a thing exists).