How do I calculate an average from averages in a dictionary with multiple values in each key without-CodePudding

Credits to someone who helped me in a previous post, I am able to find the averages of each class in the dictionary and print out the average of the averages with this code:

def avg(classes):
    average = {}
    for classnames, grades in classes.items():
        average[classnames] = sum(grades) / len(grades)
    return average

classes = {"Spanish II": [100, 99, 100, 98], "US History I": [95, 96, 97, 94]}
averages = avg(classes)
print("Average grades in each class:", averages)

average_of_averages = sum(averages.values())/len(averages)
print("Average of average grades:", average_of_averages)

I just want to know if there is a way to calculate the averages (for both the average grade in each class and the average of those averages totaled together) without using the built-in function sum().

I'm thinking I need a nested for loop: one loop for an average in each class and then another loop to find the average of these averages, but I don't know how to do this because there's multiple values in each key.

CodePudding user response：

why not use pandas instead it is much simpler and faster then using loops. Here's the code you will need to use:

import pandas as pd

classes = {"Spanish II": [100, 99, 100, 98], "US History I": [95, 96, 97, 94]}

df = pd.DataFrame(classes)

avg = df.mean()

avg_of_avg = avg.mean()

CodePudding user response：

you can use numpy.mean() and cast averages.values() to list

import numpy as np
def avg(classes):
    average = {}
    for classnames, grades in classes.items():
        average[classnames] = np.mean(grades)
    return average

classes = {"Spanish II": [100, 99, 100, 98], "US History I": [95, 96, 97, 94]}

averages = avg(classes)
print("Average grades in each class:", averages)

average_of_averages = np.mean(list(averages.values()))
print("Average of average grades:", average_of_averages)

CodePudding user response：

Yes, you can simply add a second loop as follows:

def avg(classes):
    average = {}
    for classnames in classes:
        total = 0
        for grade in classes[classnames]:
            total  = grade        
        average[classnames] = total / len(classes[classnames])
    return average

classes = {"Spanish II": [100, 99, 100, 98], "US History I": [95, 96, 97, 94]}
averages = avg(classes)
print("Average grades in each class:", averages)

total_averages = 0
for classname in averages:
    total_averages  = averages[classname]
average_of_averages = total_averages / len(averages)

print("Average of average grades:", average_of_averages)

If you would like, you can also completely skip the part of calculating each of the individual class averages, and just calculate the entire average at once as follows:

def avg(classes):
    total = 0
    total_length = 0
    for classnames in classes:
        for grade in classes[classnames]:
            total  = grade        
        total_length  = len(classes[classnames])
    return total / total_length

classes = {"Spanish II": [100, 99, 100, 98], "US History I": [95, 96, 97, 94]}
average_of_averages = avg(classes)
print("Average of average grades:", average_of_averages)