枚举字典的值

Question

I am editing such a dict and am planning to enumrate the values.

梁宁_产品思维30讲 = {
'发刊词':['产品能力是每个人的底层能力', '案例:用户体验与结婚教练'],
'同理心':['同理心训练:怎样理解愉悦与不爽', '同理心训练:怎样理解愤怒与恐惧', '同理心训练:产品要顺应用户潜意识', '认清人的本性,理解角色化生存', '自我与自律, 哪一种更贴近产品精神'],
'机会判断':['机会判断:点线面体的战略选择', '机会判断:怎样找到有势能的趋势', '痛点,痒点,爽点,都是产品机会', '两套经典的用户画像', '设计产品时要包括产品的场景'],
'系统能力':['怎样用系统能力给人提供确定性', '系统效率:小米效率的革命', '系统世界观:微信/米聊/陌陌','系统迭代:微信红包的意外与刻意', '系统生死线:猎豹和它的关键任务'],
'用户体验':["用'用户价值公式'衡量创新", "用'交叉视角'跨界创新", '怎样从新要素到新物种', '三级火箭:深度讲解互联网降维打击', '颠覆式创新:成败价值网'],
'产品世界观':['从产品中的微观, 中观和宏观视角', '人生逻辑大于商业逻辑', '产品连接客观世界/过去与将来']}

Firstly, I keep its order using OrderedDict

from collections import OrderedDict
d = OrderedDict(梁宁_产品思维30讲)

Secondly, enumerate with dict comprehension

In [46]: {k:list(enumerate(v,start=1)) for item in d.items() for k, v in item}
ValueError: too many values to unpack (expected 2)

Unfortunately, I have to try a complicated method.

new_d = {}
for item in d.items():
    for k, v in item:
        new_item = {k:list(enumerate(v, start=1))}
    new_d.update(new_item)

it reported the same error again with

ValueError: too many values to unpack (expected 2)

What's the problem with my solutions?

Answer 1

You can extract keys and values directly during the iteration over your dictionary:

new_d = {}
for k, v in d.items():
    new_item = {k:list(enumerate(v, start=1))}
    new_d.update(new_item)

print(new_d)

This translates into your dictionary comprehension as

{k:list(enumerate(v,start=1)) for k, v in d.items()}

In your code item is a tuple, representing a key, value pair. You now tell Python to iterate over the tuple with your line

 for k, v in item:

and unpack values from each element for exactly two variables. That fails, because your key is longer than just two characters. You can see a simulation of this behaviour in the following example (I use here a list of tuples, because the order in a dictionary is not defined):

dict_item = [("AB", [3, 4], "a7"), ("xy", "12"), ("de", [5, 6, 7], 43)]

for item in dict_item:
    for k, v in item:
        print(k, v)

As you can see, everything works fine, as long as the elements are iterable (string or list) and have exactly two elements to unpack. If the element is not iterable (like the integer 43 ), Python tells you that the object is not iterable. If the element is longer, it tells you that there are more values than expected from the variables - your "too many values to unpack (expected 2)" error message. The opposite can happen, too, that there are less values than variables. Then you would get the error message "not enough values to unpack (expected 2, got 1)".