rick wrote:
> Hello Everyone,
>
> I think my approach is all wrong, but here goes.
>
> var1 = []; var2 = []; var3 = []; . . . ~50 lists
>
>
> each variable would be a list of two digit integers, or two digit
> integers stored as strings (I don't need to do any math, I just need to
> know which integers are in which variable)
>
> container = [var1,var2,var3 . . . ]
>
> I'd like to be able to iterate over container or pick out one or more of
> my lists to write out an input (text) file for an external program.
>
> The thing is, assigning all those lists to a list gives me a list of
> lists, not a list of my variable names. Worse, I may or may not be able
> to have changes to a list show up in my list of lists, depending on how
> & when I do it.
>
> Really kludgy, but it is a one off that will likely never be used again.
You typically don't make 50 variables in Python, you use a dict:
>>> container = {
... "foo": [10, 20],
... "bar": [30, 40],
... "baz": [40, 50],
... #...
... }
you can then look up the "foo" list with
>>> print(container["foo"])
[10, 20]
If you want to know all the keys that 40 is associated with you can either
iterate through the items every time
>>> print([k for k, v in container.items() if 40 in v])
['bar', 'baz']
or build the reverse dict once
>>> for k, values in container.items():
... for v in values:
... value_to_key.setdefault(v, set()).add(k)
...
and then profit from fast lookup
>>> print(value_to_key[40])
{'bar', 'baz'}
>>> print(value_to_key[10])
{'foo'}
until you make changes to the original `container` dict.
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