Excluding Python Lists With Empty Values

Question

I have two lists, if list has data, I want to create a variable and assign it a name. If not, I want to disregard it. I then want to combine the list names into one list.

I'm having difficulty returning an empty value if there is no data in the list.

countries = ['America', 'France']
cities = []

if len(countries) != 0:
    country_name = 'country'
else:
    country_name = None
if len(cities) != 0:
    city_name = 'city'
else:
    city_name = None

region_names = [country_name, city_name]

Getting:

['country', None]

Want:

['country']

JJ Hassan · Accepted Answer · 2021-02-21 18:33:42Z

2

The reason this isn't working the way you want is None is still a NoneType object. So you can have a list of NoneType objects, or NoneType objects mixed with other types such as strings in your example.

If you wanted to keep the structure of your program similar, you could do something like

countries = ['America', 'France']
cities = []
region_names = []

if len(countries) != 0:
    region_names.append('country')

if len(cities) != 0:
    region_names.append('city')

in this example we declare region_names up front and only append to the list when our conditions are met.

answered Feb 21, 2021 at 18:33

JJ Hassan

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