Dictionaries and for loops hurt my soul

Question

Honestly im completely lost for what im doing wrong at this point. Dictionaries confuse the living hell out of me and working them with for loops makes it even worse. I don't even know how half of this works, im suprised it works at all, especially the stuff in normal brackets. If anyone has any advice on this it would be much appreaciated

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 here.
# 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 here.
def num_teachers(teacher_dict):
    return len(teacher_dict)

def num_courses(teacher_dict):
    course_total = 0 
    for teacher in teacher_dict:
        for course in teacher_dict[teacher]:
            course_total += 1
    return course_total

def courses(teacher_dict):
    course_list = []
    for teacher in teacher_dict:
        for course in teacher_dict[teacher]:
            course_list.append(course)
    return course_list

def most_courses(teacher_dict):
    max_value = 0
    for key in teacher_dict:
        for course in teacher_dict[key]:
            if len(course) > max_value:
                max_value = len(course)
                name = key
    return name

Answer 1 · 2018-04-30T23:19:41Z

April 30, 2018 11:19pm

HI Ian,

First, I'd like to reassure you that you're not alone. Many of us have found dictionaries to be one of the hardest data structures to get comfortable with. It really does get easier with practice though. In the meantime, don't be afraid to keep a little 'cheat sheet' of how to do common tasks with dictionaries. When you're learning a new language, there's too much to keep it all in your head at once.

As for your specific code here, you've almost got it. You just made it a little harder for yourself by getting the longest named course instead of the longest list of courses. You don't need the inner loop, you just need to get the length of the value in teacher_dict at position key (you've already successfully accessed that value to build your inner loop) and then update your max_value with that length.

For the future, there is another convenience syntax for dealing with both the key and the value when iterating through a dictionary. Instead of for key in dictionary you can use for key, value in dictionary.items() (maybe another thing for the cheat sheet) and then inside your loop you have direct access to the value as the value variable instead of needing to get it from looking it up with the key each time dictionary[key].

Hope that helps,

Alex

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Ian Cole

Ian Cole

Dictionaries and for loops hurt my soul

1 Answer

Alex Koumparos

Alex Koumparos

Ian Cole

Ian Cole