Question

Lloyd = {
    "name":"Lloyd",
    "homework": [90,97,75,92],
    "quizzes": [ 88,40,94],
    "tests": [ 75,90]
    }
Alice = {
    "name":"Alice",
    "homework": [100,92,98,100],
    "quizzes": [82,83,91],
    "tests": [89,97]
    }
Tyler = {
    "name":"Tyler",
    "homework": [0,87,75,22],
    "quizzes": [0,75,78],
    "tests": [100,100]
    }

def average(value):
    avg=0
    items = len(value)
    for item in value:
        avg +=item 
    return avg/items

def getAverage(dictin):
    hw = average(dictin.get('homework'))
    quiz = average(dictin.get('quizzes'))
    tests = average(dictin.get('tests'))
    weighted_average = hw*.1 + quiz*.3 + tests*.6
    return weighted_average

def getLetterGrade(score):
    if score >=90:
        return "A"
    elif score < 90 and score >= 80:
        return "B"
    elif score < 80 and score >= 70:
        return "C"
    elif score < 70 and score >= 60:
        return "D"
    elif score < 60:
        return "F"
    else:
        return "No grades for you"

score = getAverage(Lloyd)
grade = getLetterGrade(score)
print grade

This works fine but I am told that in the case of the score being 89.5, it would not work. I tried that as well but I am not able to find out where the problem could be. Any mistakes are welcome.

Answer 1

The catch is probably in the average function where you divide an integer (avg) by another integer (items). Since both operands are integers, Python casts the result to an integer as well, thus the average function will never return fractional scores.

There are many possible solutions:

1. Cast one of the operands (either avg or items) to a float before dividing; e.g. return float(avg)/items, or return (avg+0.0)/items.

2. Let avg start from 0.0 instead of 0 – this ensures that avg is always a float.

3. Add from __future__ import division to the very beginning of your code. This instructs Python to use division in the Python 3.x way and always return a float.

Update: also, according to MrGingerbear’s comment, you might consider rounding the score up or down in getLetterGrade. If you import the ceil and floor functions from the math module, you can say ceil(score) to round it up, floor(score) to round it down, or round(score) to round it to the nearest integer.