How can I dynamically create a name of a variable in Python?

Question

I am having a function in python

def func(dataFrame,country,sex):
    varible_name=dataFrame[(dataFrame['land']==country) & (dataFrame['sex']==sex)]

Now, for example, I call this function

func(dataFrame,'England','M')

I want that variable name be England_M instead of variable_name.

Why do you want to do this? That is a bad design pattern. You can get close to this by using a dictionary; `mydict = {England_M: myvalue}`. That gives you almost all the advantages of what you ask without the disadvantages. — Rory Daulton, Feb 05 '18 at 12:34
Use a dictionary (by the way, this is a legitimate question, so just ignore those dislikes). — goodvibration, Feb 05 '18 at 12:35
Thanks all for your comments. So, probably it's a bad idea to do so. I did find many links suggesting to use dictionary. Probably that remains the best option. — cph_sto, Feb 05 '18 at 12:37
If you really want an underscore, try something like: `my_dict['{}_{}'.format(country, sex)] = ...` — Martin Evans, Feb 05 '18 at 12:39
Yes, that's what Arnaud is also suggesting below. Thanks a ton. — cph_sto, Feb 05 '18 at 12:40
@Martin In a hypothetical variable name, yes; but just to create a dict key, a tuple is probably better. — deceze, Feb 05 '18 at 12:41

arnaud · Answer 1 · 2018-02-05T12:38:25.657

1

You can't do that in Python. What you can do instead is store the results under a dictionary with key = England_M for instance.

In your case, you could do the following :

def func(dataFrame,country,sex):
    tmp = dataFrame[(dataFrame['land']==country) & (dataFrame['sex']==sex)]
    variable_name = "{c}_{s}".format(c=country, s=sex)
    return dict(variable_name=tmp)

Now using it :

results = func(dataFrame, "England", "M")
print(results['England_M'])

edited Feb 05 '18 at 12:38

answered Feb 05 '18 at 12:34

arnaud

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you *can* but you *shouldn't* – Ma0 Feb 05 '18 at 12:35
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@Ev.Kounis yea like that `locals()['my_var_name']='some_vale'` – Take_Care_ Feb 05 '18 at 12:37
@Ev.Kounis oh wow, didn't even know about that. Yep, doesn't seem like a safe option. – arnaud Feb 05 '18 at 12:40
Thanks folks for suggestions. It seems these work arounds should work. – cph_sto Feb 05 '18 at 12:42
@Oliver Note that using a dict is not a "workaround"; it's *sane design*. "Variable variables" are a workaround for not using appropriate data structures. – deceze Feb 05 '18 at 12:43
1

Yes, you are indeed right. I agree. My apologies! Thanks a lot for your inputs. – cph_sto Feb 05 '18 at 12:45

How can I dynamically create a name of a variable in Python?

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