字典python除零错误除

Question

def getSortedKeyList(dl): 
    kl = list(dl.items()) 
    kl.sort() 
    return kl 

def tupleListToDict(a): 
    b = {} 
    for k, v in a: 
     b[k] = b.get(k, [])+v 
    return b 

def main(): 
    gradeList = [('Zaphod', [33, 20]), ('Zaphod', [75, 48]), \ 
       ('Slartibartfast', []), ('Trillian', [98, 88]), \ 
       ('Trillian', [97, 77]), ('Slartibartfast', []), \ 
       ('Marvin', [2000, 500]), ('Authur', [42, 20]), \ 
       ('Authur', [64]), ('Trillian', [99]), \ 
       ('Marvin', [450]), ('Marvin', [550]), \ 
       ('Agrajag', []), ('Agrajag', []), ('Agrajag', [0]), \ 
       ('Ford', [50]), ('Ford', [50]), ('Ford', [50])] 

    print('\t', '\t', "Grade", '\t') 
    print('\t', "Name", '\t', "Count", '\t', "Average") 
    print("-----------------------------------------") 

    dicList = tupleListToDict(gradeList)    
    dicList = getSortedKeyList(dicList) 

    for k, v in dicList: 
     print(k, len(v), '\t', sum(v)/len(v)) 

我想从字典中创建一个表。首先，我将元组转换为字典并按键对字典进行排序。接下来，我试图打印出（密钥，密钥数量，平均值）。但是，当我尝试对平均部分进行求和（v）/ len（v）时，我得到了除零误差。为了避免这个错误，我尝试将字典中的空值返回到0，但我不知道如何去做。请帮忙。

Answer 1

def getSortedKeyList(dl): 
    kl = list(dl.items()) 
    kl.sort() 
    return kl 

def tupleListToDict(a): 
    b = {} 
    for k, v in a: 
     b[k] = b.get(k, [])+v 
    return b 

def main(): 
    gradeList = [('Zaphod', [33, 20]), ('Zaphod', [75, 48]), \ 
       ('Slartibartfast', []), ('Trillian', [98, 88]), \ 
       ('Trillian', [97, 77]), ('Slartibartfast', []), \ 
       ('Marvin', [2000, 500]), ('Authur', [42, 20]), \ 
       ('Authur', [64]), ('Trillian', [99]), \ 
       ('Marvin', [450]), ('Marvin', [550]), \ 
       ('Agrajag', []), ('Agrajag', []), ('Agrajag', [0]), \ 
       ('Ford', [50]), ('Ford', [50]), ('Ford', [50])] 

    print('\t', '\t', "Grade", '\t') 
    print('\t', "Name", '\t', "Count", '\t', "Average") 
    print("-----------------------------------------") 

    dicList = tupleListToDict(gradeList)    
    dicList = getSortedKeyList(dicList) 

    for k, v in dicList: 
     try: 
      print(k, len(v), '\t', sum(v)/len(v)) 
    except ZeroDivisionError as detail: 
      print('Handling run-time error:', detail) 

您可以通过try和catch块捕获异常ZeroDivisionError;

Answer 2

Slartibartfast没有档次，从而len(v)是0，当你到他的纪录。

根据他的“平均”应该是什么，你可以修改的最后一个循环，是这样的：

for k, v in dicList: 
    print(k, len(v), '\t', sum(v)/len(v) if len(v)>0 else 'N/A')