codecademy_python_Student Becomes the Teacher

lloyd = {
    "name": "Lloyd",
    "homework": [90.0,97.0,75.0,92.0],
    "quizzes": [88.0,40.0,94.0],
    "tests": [75.0,90.0]
}
alice = {
    "name": "Alice",
    "homework": [100.0, 92.0, 98.0, 100.0],
    "quizzes": [82.0, 83.0, 91.0],
    "tests": [89.0, 97.0]
}
tyler = {
    "name": "Tyler",
    "homework": [0.0, 87.0, 75.0, 22.0],
    "quizzes": [0.0, 75.0, 78.0],
    "tests": [100.0, 100.0]
}


students = [lloyd, alice, tyler]

for i in range(0,3):    #range含头不含尾，同时注意不要写成for i in students，这里的循环其实可以类比为for(i=0;i<xx;i++)...同时参数也可以更灵活用len(students)来获取
    print students[i]["name"]
    print students[i]["homework"]
    print students[i]["quizzes"]
    print students[i]["tests"]
    
def average(numbers):
    total = sum(numbers)
    total = float(total)
    return total/len(numbers)
    
def get_average(student):
    homework = average(student["homework"])
    quizzes = average(student["quizzes"])
    tests = average(student["tests"])
    
    return 0.1*homework + 0.3*quizzes + 0.6*tests
    
def get_letter_grade(score):
    if score >= 90:
        return "A"
    elif score >= 80:
        return "B"
    elif score >= 70:
        return "C"
    elif score >= 60:
        return "D"
    else:
        return "F"
        
print get_letter_grade(get_average(lloyd))    

def get_class_average(students):
    results = []
    for student in students:
        results.append(get_average(student))
    return average(results)
    
avg = get_class_average(students)
print avg
print get_letter_grade(avg)

```python

range 扩展

range(6) # => [0,1,2,3,4,5]
range(1,6) # => [1,2,3,4,5]
range(1,6,3) # => [1,4]