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

Alejandro Byrne
Alejandro Byrne
2,562 Points
Posted by Alejandro Byrne
Alejandro Byrne
2,562 Points

How to loop for item in an item

Hi, I think I have the challenge down, just not sure how to do a for loop for an item in an item - probably did it wrong. Any help? Thanks.

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(topics):
    result = []
    for item in item in COURSES:
        if topics in item:
            result.append(item)
    return result

1 Answer

Jeff Wilton
Jeff Wilton
16,646 Points
Jeff Wilton
Jeff Wilton
16,646 Points

You are on the right track! When you iterating through a loop, think of it as 'for item in collection', not 'for item in item'. In this example, it is actually 'for item in collection in collection'.

When doing list comprehension on a Set for example, you can simply say 'for item in collection', but since we want to use both the key and the value of the inner dictionary, we want this syntax: 'for key, value in dictionary.items()'.

Here is how the corresponding code would look:

def covers(topics):
    result = []
    for topic in topics:
        for course_key, course in COURSES.items():
            if topic in course:
                result.append(course_key)
    return result
Alejandro Byrne
Alejandro Byrne
2,562 Points
Alejandro Byrne
Alejandro Byrne
2,562 Points

Ahhhh... yes, forgot to add the .items() for dictionaries. And didn't think really know about the way of checking in a loop, thanks!