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Python Python Collections (2016, retired 2019) Dictionaries Teacher Stats

Steven Olick
Steven Olick
1,561 Points
Posted by Steven Olick
Steven Olick
1,561 Points

does not iterate through all values?

Hello. I've moved forward and solved this another way, but still don't quite get why this doesn't work to return the total number of values. I've also been doing this for around 4 hrs now so I could just be making a silly mistake. Thanks

teachers.py 
# The dictionary will look something like:
# {'Andrew Chalkley': ['jQuery Basics', 'Node.js Basics'],
#  'Kenneth Love': ['Python Basics', 'Python Collections']}
#
# Each key will be a Teacher and the value will be a list of courses.
#
# Your code goes below her
def num_teachers(my_dictionary):
    return int(len(my_dictionary.keys()))

def num_courses(my_dictionary):
    return int(len(my_dictionary.values()))

2 Answers

Aaron Price
Aaron Price
5,974 Points
Aaron Price
Aaron Price
5,974 Points

I'm sure there's a more elegant way to do this, but it works. 

def num_courses(my_dictionary):
    count = 0

    for teacher in my_dictionary:
        count += len(my_dictionary[teacher])

    return count
Steven Olick
Steven Olick
1,561 Points
Steven Olick
Steven Olick
1,561 Points

Thanks, Aaron. That was pretty much what I ended up writing to get through it. Always helps to see someone else had the same logic!

Jeremy Schaar
Jeremy Schaar
4,728 Points
Jeremy Schaar
Jeremy Schaar
4,728 Points

Hey Steven,

I'm just working through the challenge as well, so may not be the best to give advice, but looks to me like you're counting the number of values, not the number of items in each value. Python says "Andrew Chalkley" has one value ('jQuery Basics' and 'Node.js Basics'), and "Kenneth Love" has one value (Python Basics' and 'Python Collections'). So the length will be 2 (not 4).

I think Aaron's solution is the one they thought we were most likely to get to, but I'll just add in that the below also works. (I found it by googling and then had some fun reading up on the map function;) )

def num_courses(arg1):
    return sum(map(len, arg1.values()))
Steven Olick
Steven Olick
1,561 Points
Steven Olick
Steven Olick
1,561 Points

Thanks, Jeremy! I have seen the map() before but didn't read into it much. Won't hurt I'll need to learn it sometime!