我在 python 中没有得到正确的字典和列表输出

Question

roll_number = [47, 64, 69, 37, 76, 83, 95, 97]
sample_dict = {'Jhon':47, 'Emma':69, 'Kelly':76, 'Jason':97}
 
for a in roll_number:
    if a not in sample_dict.values():
        roll_number.remove(a)

print(roll_number)

我的输出是 [47, 69, 76, 95, 97] 而不是 [47, 69, 76, 97]。谁能解释一下？

Answer 1

您可以使用set 来“冻结”数组并安全地删除其值：

roll_number = [47, 64, 69, 37, 76, 83, 95, 97]
sample_dict = {'Jhon':47, 'Emma':69, 'Kelly':76, 'Jason':97}

roll_set = set(roll_number)
for a in roll_number:
    if a not in sample_dict.values():
        roll_set.remove(a)

print(roll_set)

它将打印{97, 69, 76, 47}。如果你想要一个列表，你可以使用list(roll_set)。