我在Python中使用字典，经常遇到这样的问题：“列表索引必须是整数或切片，而不是str”该怎么办？

Question

>>> d = {'year':[{'season':['winter',['spring']]}]}
>>> d['year']['season']['winter']
Traceback (most recent call last):
  File "<python-input-2>", line 2, in <module>
    d['year']['season']['winter']
    ~~~~~~~~~^^^^^^^^^^
TypeError: list indices must be integers or slices, not str

我尝试更改变量的名称，但没有任何作用。我需要做什么才能“拔出”“弹簧”？

Answer 1

键

year

的值是一个列表，所以需要对列表进行索引。 一步一步来吧：

>>> d = {'year':[{'season':['winter',['spring']]}]}
>>> d['year']  # result is list
[{'season': ['winter', ['spring']]}]
>>> d['year'][0]  # result is dict
{'season': ['winter', ['spring']]}
>>> d['year'][0]['season']  # result is list
['winter', ['spring']]
>>> d['year'][0]['season'][1]  # result is another list
['spring']
>>> d['year'][0]['season'][1][0]  # result is string
'spring'