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

Waleed Aljarman
PLUS
Waleed Aljarman
Courses Plus Student 947 Points
Posted by Waleed Aljarman
Waleed Aljarman
Courses Plus Student 947 Points

teacher dict

i gave up on the last one, how i can do it ?

teachers.py 
def num_teachers(t_dict):
    return len(t_dict)

def num_courses(t_dict):
    courses=0
    for value in t_dict.values():
        courses += len(value)
    return courses

def courses (t_dict):
    c_list=[]
    for value in t_dict.values():
        c_list.append(value)
    other=[]
    for i in c_list:
        other.extend(i)
    return other

def most_courses(t_dict):
    most_course = 0 
    newTeacher = ""  
    for teacher in t_dict: 
        if len(t_dict[teacher]) > most_course: 
            most_course = len(t_dict[teacher]) 
            newTeacher = teacher
    return newTeacher 

def stats(t_dict):

2 Answers

Jeff Muday
MOD
Jeff Muday
Treehouse Moderator 28,720 Points
Jeff Muday
Jeff Muday
Treehouse Moderator 28,720 Points

You got pretty far in that challenge. The solution to the challenge is to start a new empty "stats" list. Then you iterate over the "items" in each dictionary entry as a key/value pair. Finally, append the stats list with a list of just the teacher name and the class count.

Here is an example... it is not the solution, but you can use a similar approach you can use to solve the last part of the challenge.

Suppose we had a list of artists and vinyl albums-- and wanted a list of lists with the artist and the number of albums in your collection.

my_music = {'Beatles': ['Hard Days Night','Help','Abbey Road'], 'Pink Floyd': ['Dark Side of the Moon','The Wall']}

def music_stats(music_dict):
    artist_stats = []
    # the for loop iterates over the key/value pairs (items) in the list.
    for artist, albums in music_dict.items():
        artist_stats.append([artist, len(albums)]

    return artist_stats
Waleed Aljarman
Waleed Aljarman
Courses Plus Student 947 Points
Waleed Aljarman
Waleed Aljarman
Courses Plus Student 947 Points

i didn't understand what you did in the for loop statement, what does artist, mean. and just for clarification, is my_music the same as music.dict ?

Jeff Muday
MOD
Jeff Muday
Treehouse Moderator 28,720 Points
Jeff Muday
Jeff Muday
Treehouse Moderator 28,720 Points

The impressive feature of the iterator music_dict.items() is that it returns key-value "pairs". Each time the key is matched with the value it holds.

For example

    for key, value in music_dict.items():
        print 'key = ', key
        print 'value = ', value

The first time it goes through--

key = 'Beatles' value = ['Hard Days Night','Help','Abbey Road']

The second time it goes through

key = 'Pink Floyd' value = ['Dark Side of the Moon','The Wall']

We can use this feature to open the list of teachers and their associated courses

# this works in Python 2.7.x, you should use different syntax in Python 3.x for print statements
t_dict = {'Andrew Chalkley': ['jQuery Basics', 'Node.js Basics'], 'Kenneth Love': ['Python Basics', 'Python Collections']}

for name, classes in t_dict.items():
    print 'name = ', name
    print 'classes = ', classes
    count = len(classes)
    print "{} teaches {} classes".format(name,count)

You can encapsulate this approach into the function "stats()"

def stats(t_dict):
    stats_list = []
    for name, classes in t_dict.items():
        stats_list.append([name,len(classes)])
    return stats_list