I am trying to do the following in a concise way:
n = 3
lst1 = [[] for _ in range(n)]
lst2 = [[] for _ in range(n)]
lst3 = [[] for _ in range(n)]
Basically generating a number of list of empty lists with the same size.
I am looking for a one-liner on this one. I tried using zip and various itertools but I must admit this set of features is one of my weak links with Python.
You can achieve the same with just one additional layer of list comprehension or generator expression and then unpacking it to variables:
>>> n = 3
>>> lst1, lst2, lst3 = ([[] for _ in range(n)] for _ in range(3))
>>> lst1
[[], [], []]
n?
range(n) is wrong. It should be as many as the number of vars to unpack there are, so in this case 3.
n or hasn't been stated, changed example accordingly.n like you said.n had something to do with list size and the number of them, changed the answer accordingly.Instead of storing the lists in different variables, I will suggest to wrap all the list within single list. Your code should be like:
>>> num_of_list, size_of_list = 5, 3
>>> my_list = [[[] for _ in range(size_of_list)] for _ in range(num_of_list)]
The value hold by my_list will be:
[
[[], [], []],
[[], [], []],
[[], [], []],
[[], [], []],
[[], [], []]
]
For accessing each sub-list, you may simply use the index as:
>>> my_list[0]
[[], [], []]
>>> my_list[1]
[[], [], []]
If it is MUST to store the values in separate variables, you may unwrap the content of main list to individual variables as:
list1, list2, list3, list4, list5 = my_list
lst1, lst2, etc... in practice they're going to be entirely separate (conceptually) ones, so it would not be a good idea to throw them in the same structure.raw_list and then unwrap the values to variables for better clarity. My this comment is opinion based.teams, scores and dates. That's what you want. Not a raw_list with 3 sublists. What are you even going to do with raw_list? In this case, it serves no purpose, so why not just do what the other answer suggested?n = 3
for i in range(1, n+1):
exec("lst%s = [[] for _ in range(%s)]" % (i, n))
Based on To convert string to variable name
lst1,lst2different instances of list?n? Or, you could even store these lists in another list? It all depends on how many lists do you need.