python using variables from another file

Question

I’m new and trying to make a simple random sentence generator-
How can I pull a random item out of a list that is stored in another .py document?
I’m using

random.choice(verb_list)

to pull from the list. How do I tell python that verb_list is in another document?

Also it would be helpful to know what the principle behind the solution is called. I imagine it’s something like ‘file referencing’ ‘file bridging’ etc..

Asked By: Benjamin James

||

Source

Answer 1

It’s called importing.

If this is data.py:

verb_list = [
    'run',
    'walk',
    'skip',
]

and this is foo.py:

#!/usr/bin/env python2.7

import data
print data.verb_list

Then running foo.py will access verb_list from data.py.

You might want to work through the Modules section of the Python tutorial.

If verb_list is stored in a script that you want to do other things too, then you will run into a problem where the script runs when all you’d like to do is import its variables. In that case the standard thing to do is to keep all of the script functionality in a function called main(), and then use a magic incantation:

verb_list = [
    'run',
    'walk',
    'skip',
]

def main():
    print 'The verbs are', verb_list

if __name__ == '__main__':
    main()

Now the code in main() won’t run if all you do is import data. If you’re interested, Python creator Guido van Rossum has written an article on writing more elaborate Python main() functions.

Answered By: andrewdotn

Answer 2

You can import the variables from the file:

vardata.py

verb_list = [x, y, z]
other_list = [1, 2, 3]
something_else = False

mainfile.py

from vardata import verb_list, other_list
import random

print random.choice(verb_list)

you can also do:

from vardata import *

to import everything from that file. Be careful with this though. You don’t want to have name collisions.

Alternatively, you can just import the file and access the variables though its namespace:

import vardata
print vardata.something_else

Answered By: Kartik

python using variables from another file

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