从Python列表中的项目创建新的空列表？

Question

my_list = ['c1','c2','c3']

Is there anyway to create a certain amount of new lists based on items inside of a list?

Result would be:

c1 = []
c2 = []
c3 = []

Answer 1

You can do that using globals() :

>>> my_list = ['c1','c2','c3']
>>> for x in my_list:
...     globals()[x] = []
...     
>>> c1
[]
>>> c2
[]
>>> c3
[]

But it's better to use a dict here:

>>> dic = {item : []  for item in my_list}
>>> dic
{'c2': [], 'c3': [], 'c1': []}

Answer 2

Instead of creating new global variables using the names from your list, I would suggest using a dictionary:

my_list = ['c1', 'c2', 'c3']
my_dict = {k: [] for k in my_list}

Then to access one of those lists you could use something like my_dict['c1'] or my_dict['c2'] .

Another solution would be to add the new lists as attributes to some object or module. For example:

lists = type('Lists', (object,), {k: [] for k in my_list})

After which you could access your lists using lists.c1 , lists.c2 , etc.

In my opinion both of these methods are cleaner than modifying globals() or locals() and they give you very similar behavior.

Note that if you are on Python 2.6 or below you will need to replace the dictionary comprehensions with dict((k, []) for k in my_list) .