List 计数“的数量；通行证；在循环中

这是我的代码，简而言之，它从csv文件导入数据，读取数据，并根据csv文件中存储的两个分数确定学生的百分比和分数。我想做的是找到并存储有多少个A、B、C、D等级和不合格，然后在最后以“有2个A等级”“有4个B等级”等方式输出它们

提前谢谢你的帮助

import csv

with open ("UASHSDDP3efiles.csv", "r") as csvfile: #Reads the csv file and puts the names into a list
    reader = csv.reader(csvfile)
    list0 = []
    for row in reader:
        list0.append(row[0])

with open ("UASHSDDP3efiles.csv", "r") as csvfile: #Reads the csv file and puts the prelim marks into a list
    reader = csv.reader(csvfile)
    list1 = []
    for row in reader:
        list1.append(row[1])

with open ("UASHSDDP3efiles.csv", "r") as csvfile: #Reads the csv file and puts the coursework marks into a list
    reader = csv.reader(csvfile)
    list2 = []
    for row in reader:
        list2.append(row[2])

list3 = [(int(x) + int(y)) for x, y in zip(list1, list2)] #Creates a list with each set of marks added together

for i in range(len(list3)): #Creates a loop to go through the list
    totalmark = list3[i] #Takes the first piece of data and calls it totalmarks, on the second loop, it will be the second piece of data and so on...
    percentage = (totalmark / 150) * 100 #Finds the percentage of their total mark out of 150

    if percentage >=  70: #Checks if they have received an A grade
        grade = "A"
    if 60 <= percentage < 70: #Checks if they have received a B grade
        grade = "B"
    if 50 <= percentage < 60: #Checks if they have received a C grade
        grade = "C"
    if 45 <= percentage < 50: #Checks if they have received a D grade
        grade = "D" 
    if percentage < 45: #Checks if they haven't received a grade
        grade = "No grade"

    roundedpercentage = round(percentage) #Rounds the percentage to the nearest integer
    print(list0[i],"'s percentage was", roundedpercentage,"%", "and their grade was:", grade) #Prints the pupils name, percentage and grade

max=max(list3) #Finds the highest mark
print("The highest mark achieved was:", max)
min=min(list3) #Finds the lowest mark
print("The lowest mark achieved was:", min)

---

您可以创建一个dict，将等级作为键，并为遇到的每个等级增加值。for循环变为（为了可读性，对代码进行了一些简化）：

然后，在脚本末尾：

for grade in ('A', 'B', 'C', 'D'):
    print("There were %d %s passes" % (gradescount.get(grade, 0), grade))
print("There were %d fails" % (gradescount.get('No grade', 0),))

---

希望这就是你想要的。

制作一个由五个元素组成的数组a=np.zero（5）。在每一个等级中，制定代码

如果百分比>=70：
等级=“A”
ind=作战需求文件（等级）-作战需求文件（“A”）
a[ind]=a[ind]+1

在cae中的其他情况，即无等级 使

a[4]=a[4]+1

。您将得到一个包含所需答案的数组

# create the dict first
gradescount = dict()

for student, totalmark in zip(list0, list3): # iterate directly over the lists
    percentage = (totalmark / 150) * 100
    if percentage >= 70:
        grade = "A"
    elif percentage >= 60:  #elif prevents extra tests
        grade = "B"
    elif percentage >= 50:
        grade = "C"
    elif percentage >= 45:
        grade = "D"
    else:
        grade = "No grade"

    # Increment appropriate grade counter
    gradescount[grade] = gradescount.get(grade, 0) + 1

    roundedpercentage = round(percentage)
    print("%s's percentage was %d%% and their grade was: %s" % (
            student,
            roundedpercentage,
            grade
    ))

for grade in ('A', 'B', 'C', 'D'):
    print("There were %d %s passes" % (gradescount.get(grade, 0), grade))
print("There were %d fails" % (gradescount.get('No grade', 0),))