Guided Project Profitable Apps Screen 12/14 #350

Q&A DQ Courses
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#1

Hello!
I figured it would be practical to create a more general function to find sum of user ratings per column index. In the exercise, we’re asked to do it directly for the prime genres column [-5] for the ios dataset.

Here is what i tried:

def ratings_per_index(dataset, index):
    dataset_freq = freq_table(dataset, index)
    for genre in dataset_freq:
        total = 0
        len_genre = 0
        for app in dataset:
            genre_app = app[index]
            if genre_app == genre:            
                n_ratings = float(app[5])
                total += n_ratings
                len_genre += 1
        avg_n_ratings = total / len_genre

Then, i tried using the function:
print(ratings_per_index(ios_final,-5))

What i expected was the same answer we’d get without the function:

genres_ios = freq_table(ios_final, -5)
for genre in genres_ios:
    total = 0
    len_genre = 0
    for app in ios_final:
        genre_app = app[-5]
        if genre_app == genre:            
            n_ratings = float(app[5])
            total += n_ratings
            len_genre += 1
    avg_n_ratings = total / len_genre
    print(genre, ':', avg_n_ratings)

What actually happened was that i got the result ‘’ None’’.

What am i doing wrong? Help is welcome!! :slight_smile:

#2

Hi @ola.grignon, maybe you rerun your code from the beginning because I just used it now and it worked perfectly.

#3

The function needs to return a value, and the value gets printed when you run

Since your function is not returning anything, it prints a None. Adding an appropriate Return statement should fix this.

Also, for future reference, please make sure to include the link to the lesson screen in your posts.