Creating empty lists base on another list name in Python

Question

The list that will be the name has the form:

 print(my_list)

I get:

[[1, 1], [1, 2], [1, 4], [2, 1], [2, 2], [2, 4], [3, 3], [3, 5], [3, 6], [4, 1], [4, 2], [4, 4], [5, 3], [5, 5], [5, 6], [6, 3], [6, 5], [6, 6]]

I would like to create empty lists based on those pair of numbers, like:

for i in my_list:
    'H'+i[0]+i[1] = []

So I would get something like this:

H11 = []
H12 = []
H14 = ...

don't use separated variables but keep on list - it will simpler to work with data. — furas, May 04 '22 at 21:42
@PranavHosangadi, I can't see how using dictionary can help, I still gonna need to write all the lists name, I trying to use `'H%' %i` but without success — lzcostademoraes, May 04 '22 at 21:49

score 3 · Accepted Answer · answered May 04 '22 at 21:47

Dynamic variable assignment as you describe it is discouraged. See How do I create variable variables?, mentioned in the comment by Pranav Hosangadi. Use a dictionary instead, and assign it using dictionary comprehension:

my_lst = [[1, 1], [1, 2], [1, 4], [2, 1], [2, 2], [2, 4], [3, 3],
          [3, 5], [3, 6], [4, 1], [4, 2], [4, 4], [5, 3], [5, 5],
          [5, 6], [6, 3], [6, 5], [6, 6]]

my_dct = { f"H{lst[0]}{lst[1]}": [] for lst in my_lst}

print(my_dct)
# {'H11': [], 'H12': [], 'H14': [], 'H21': [], 'H22': [], 'H24': [], 'H33': [], 'H35': [], 'H36': [], 'H41': [], 'H42': [], 'H44': [], 'H53': [], 'H55': [], 'H56': [], 'H63': [], 'H65': [], 'H66': []}

print(my_dct['H11'])
# []

print(my_dct['H12'])
# []

score 1 · Answer 2 · answered May 04 '22 at 21:44

1

You can do it with this:

for i in my_list:
    globals()['H'+i[0]+i[1]] = []

print(H11)
print(H12)
...

But it seems like a bad design, I think that at least you should try to find another approach.

answered May 04 '22 at 21:44

var211

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Creating empty lists base on another list name in Python

2 Answers2