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Python Python Collections (Retired) Dictionaries Teacher Stats

Posted by Atidaishe Chinodakufa
Atidaishe Chinodakufa
2,323 Points

teacher stats challenge

help! I'm stuck here.

teachers.py 
# The dictionary will be something like:
# {'Jason Seifer': ['Ruby Foundations', 'Ruby on Rails Forms', 'Technology Foundations'],
#  'Kenneth Love': ['Python Basics', 'Python Collections']}
#
# Often, it's a good idea to hold onto a max_count variable.
# Update it when you find a teacher with more classes than
# the current count. Better hold onto the teacher name somewhere
# too!
#
# Your code goes below here.
def most_classes(dicts):
  count = []
  maxclas=0
  for teacher in dicts:
    count.append(len(dicts[teacher]))
  for num in count:
      if num > maxclas:
        maxclas = count

  return teacher in maxclas==len(dicts[teacher])

13 Answers

William Li
PLUS
William Li
Courses Plus Student 26,868 Points
William Li
William Li
Courses Plus Student 26,868 Points

There're some syntax errors in your code, also, I don't 100% follow the logic of your code. But there's an obvious problem, this question is asking you to return the name of the teacher with most classes, and in your for loop, for teacher in dicts:, you only append the number of classes each teacher has into the count list, however, your code didn't keep track of the teacher's name, which is what the return value of this function is supposed to be.

def most_classes(dicts):
  most_class = ""     # holds the name of teach with most class
  max_count = 0       # max counter for classes
  for teacher in dicts:
    if len(dicts[teacher]) > max_count:
      max_count = len(dicts[teacher])
      most_class = teacher
  return most_class
Jan M
Jan M
1,053 Points

@William Li could you please explain how you arrived at that answer? Why is the max count for classes 0?

Endrin Tushe
Endrin Tushe
4,591 Points
Endrin Tushe
Endrin Tushe
4,591 Points

Could you explain the most_class = teacher part a bit more? So I get the max count part, if the length of the values in the dictionary is greater than 0 which it will be in the first iteration then the dictionary will be whatever length of the value that it was comparing against. So let's say in the first iteration the for loop compared the length of Kenneth's love value 2 against max count. Since max count is 0 it was greater, then max count became 2. On the next iteration the loop compared the length of Jason's classes which was 3, and again since that's greater than 2 the new max_count now becomes 3. Okay so far so good...but here's where I get stuck how does the most_class=teacher, associate the value of 3 in the max_count with the key of Jason Seifer in the dictionary and then appends that key to the empty string most_class?

William Li
William Li
Courses Plus Student 26,868 Points
William Li
William Li
Courses Plus Student 26,868 Points

Hi, Endrin. Your understanding of max_counter is spot-on. Now, as for the most_class.

    if len(dicts[teacher]) > max_count:
      max_count = len(dicts[teacher])
      most_class = teacher

in the dictionary and then appends that key to the empty string most_class?

No, it doesn't append the key to empty string most_class, the equal sign is assignment operator, it assigns new value to most_class, and replaced whatever old value that's currently stored in the variable. Much like assigning new numerical value to max_count, this line most_class = teacher will only run when the condition if condition is satisfied.

Say, using the examples you've given, while iterating through the dictionary, if the key "Kenneth Love" has 2 classes, and it's more than the 0 currently stored in max_count, 2 will be assigned to max_count, and the String "Kenneth Love" assigns to most_class; up next, Jason has 3 classes, then 3 will be assigned to max_count, and most_class becomes String "Jason Seifer".

The real question here is that, what purpose does most_class variable serves? Is it absolutely necessary to keep track of teacher's name every time the max_count gets assigned a new numerical value? The answer is YES. Because that's what the challenge requires you to do.

Create a function named most_classes that takes a dictionary of teachers. Each key is a teacher's name and their value is a list of classes they've taught. most_classes should return the teacher with the most classes.

The challenge asked that the return value of the function to be the name of the teacher with most classes, therefore, max_count can't be used as return value. Does that make sense?

Ryan Flyod
Ryan Flyod
1,939 Points
Ryan Flyod
Ryan Flyod
1,939 Points

Hi William,

This code doesn't seem to be accurate for me. Could you explain to me why it isn't working? Treehouse accepts it as a correct answer, but I don't think it is. Thanks. the "teacher1" key should be the answer, as it has 2 classes versus the other two keys, which have 1. 

Dict = {"teacher1": ["class1", "class2"], "teacher2": "class3", "teacher3": "class4"}

def most_courses(Dict):
    most_classes = ''
    max_count = 0
    for teacher in Dict:
        if len(Dict[teacher]) > max_count:
            max_count = len(Dict[teacher])
            most_classes = teacher
    return most_classes, max_count

returned result is 

('teacher2', 6)

indicating it grabbed the "teacher2" key because "class3" value is 6 characters long. When, in reality, it should have returned "teacher1" because it has two values, which is greater than the one value of the "teacher2" key

Abenezer Mamo
Abenezer Mamo
5,821 Points
Abenezer Mamo
Abenezer Mamo
5,821 Points

This is my solution to this problem. It's quite simple to understand and it's efficient. 

def most_classes(my_dict):
  teachers_list = {}
  for teacher in my_dict:
    teachers_list[teacher] = len(my_dict[teacher])
  return max(teachers_list, key=teachers_list.get)
Shadow Skillz
Shadow Skillz
3,020 Points
Shadow Skillz
Shadow Skillz
3,020 Points

Hey Abenezer I've been stuck on this coding challenge for longer than I like to mention. Your solution helped me pass the second step if you could or anybody for that matter break down your code line by line in detail that would be greatly appreciated thanks.

fahad lashari
fahad lashari
7,693 Points
fahad lashari
fahad lashari
7,693 Points

This is how I did it. I think this is the simplest way to achieve this task.

def most_courses(dict):
    for key, value in dict.items():
        if max(value):
            return key
Atidaishe Chinodakufa
Atidaishe Chinodakufa
2,323 Points
Atidaishe Chinodakufa
Atidaishe Chinodakufa
2,323 Points

Create a function named most_classes that takes a dictionary of teachers and returns the teacher with the most classes.

Atidaishe Chinodakufa
Atidaishe Chinodakufa
2,323 Points
Atidaishe Chinodakufa
Atidaishe Chinodakufa
2,323 Points

Ok I got it. Thanks!

Trevor Currie
Trevor Currie
9,289 Points
Trevor Currie
Trevor Currie
9,289 Points

Your return statement of python return teacher in maxclas==len(dicts[teacher]) will not search through the dicts for the teacher key that has the same length as the your maxclas variable. In order to do so, you would have to do a third for loop for this to work:

[most_classes_teacher for teacher in dict if len(dict[teacher]) == maxclas]

Not very efficient!

Jose Vicente Jonas Franca
Jose Vicente Jonas Franca
1,701 Points
Jose Vicente Jonas Franca
Jose Vicente Jonas Franca
1,701 Points 
def most_classes(teachers):
  max_count = 0
  most_class = ''
  for teacher in teachers:
    if len(teachers.get(teacher)) > max_count:
      max_count = len(teachers.get(teacher))
      most_class = teacher
  return(most_class)

This worked for me.

Oguz Dumanoglu
Oguz Dumanoglu
5,169 Points
Oguz Dumanoglu
Oguz Dumanoglu
5,169 Points

Hello guys,

I did this challenge in this way, but it did not worked. Pls help.

def most_classes(dict):
    max_count = 0
    for key in dict:
        current_count = len(dict[key])
        if max_count < current_count:
            max_count = current_count
        return key
Christopher Janke
Christopher Janke
11,054 Points
Christopher Janke
Christopher Janke
11,054 Points

I know this post is old, but I have been stuck on this for 2 days now over thinking this problem. Thank you William for this answer. It really helped me to see that I was doing way to much code for such a simple answer. You helped to me "Refactor" my thinking!

yanyan Liu
yanyan Liu
3,954 Points
yanyan Liu
yanyan Liu
3,954 Points 
          <p>
def most_courses(dict):
    list_comp = [ (teacher, len(courses) )for teacher, courses in dict.items()]
    newlist = sorted(list_comp, key=lambda tup: tup[1])    
    return newlist[-1][0]

         </p>
darcyprice
darcyprice
4,442 Points
darcyprice
darcyprice
4,442 Points

Thank you so much @William Li and @fahad Iashari!

I was able to get close on my own, but now I have figured it out :)

Andrii Gorokh
Andrii Gorokh
14,809 Points
Andrii Gorokh
Andrii Gorokh
14,809 Points

Why this doesn't work?

def most_courses(arg):
    teacher = ""
    max_count = 0
    for value in arg:
        if len(arg[value]) > max_count:
            max_count = len(arg[value])
            teacher = value
       return teacher