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

Posted by Zan Le
Zan Le
1,016 Points

Return a list of list from dictionary

Hi, in the stats function, after I create a new dictionary, and then convert it to a list of list using map(list, ...), it shows me the desired output. however, it does not pass the test. could you kindly help me on this please.

many 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 here.


def num_teachers(string):
    return len(string)

def num_courses(string):
    course_list=[]
    for x in string.values():
        for y in x:
            if y not in course_list:
                course_list.append(y)
    return len(course_list)

def courses(string):
    course_list=[]
    for x in string.values():
        for y in x:
            if y not in course_list:
                course_list.append(y)
    return course_list

def most_courses(string):
    maxcount = max(len(value) for value in string.values())
    return "".join([k for k, value in string.items() if len(value) == maxcount])

def stats(string):
    new_dict = {k: len(v) for k,v in dict.items()}
    new_list = map(list, new_dict.items())
    return new_list

2 Answers

Krishna Pratap Chouhan
Krishna Pratap Chouhan
15,203 Points

HINT: You missed to use "string" variable that you were taking as an argument for stats function.

solution is 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(string):
    return len(string)

def num_courses(string):
    course_list=[]
    for x in string.values():
        for y in x:
            if y not in course_list:
                course_list.append(y)
    return len(course_list)

def courses(string):
    course_list=[]
    for x in string.values():
        for y in x:
            if y not in course_list:
                course_list.append(y)
    return course_list

def most_courses(string):
    maxcount = max(len(value) for value in string.values())
    return "".join([k for k, value in string.items() if len(value) == maxcount])

def stats(dict):
    new_dict = {k: len(v) for k,v in dict.items()}
    new_list = map(list, new_dict.items())
    return new_list

btw its not a good idea to use the variable name as "dict".

Josh Bennett
Josh Bennett
15,258 Points
Josh Bennett
Josh Bennett
15,258 Points

What is going on here? .join([k for k,

I get everything else.

Krishna Pratap Chouhan
Krishna Pratap Chouhan
15,203 Points 
li = ["one", "two", "three"]
str="-and-"
str.join(li)

will give the output, 'one-and-two-and-three'.

so there is join function.

[         k for k, value in string.items() if len(value) == maxcount       ]
#we are forming the list out of "k for k, value in string.items() if len(value) == maxcount"
#the list will contain k 
#where k is the key and value is value in string dictionary.
#but only if length of value is equals to maxcount,  the k is returned and added into the list

Quite concise and good code by Zan Le.

Todd Costa
Todd Costa
3,380 Points
Todd Costa
Todd Costa
3,380 Points

Sort of an unrelated question and i understand that everyone learns at their own pace, but am i behind because i dont even think or understand how to write code that concise. I thought i was pretty good at parsing others code but the above code might as well be binary to me.

Zan Le
Zan Le
1,016 Points
Zan Le
Zan Le
1,016 Points

Thank you!

Krishna Pratap Chouhan
Krishna Pratap Chouhan
15,203 Points

Todd Costa , it takes time... You see enough of it and you start understanding it eventually. I can recall that i couldn't understand the above piece of code a while back and i struggle to understand a lot of it even now. Dont worry about that, at all.

In fact i believe, a code is good when anyone can understand it. Even those who don't understand that language should be able to make sense out of it.