Python: Interact Dropdown - how to reference the output

Question

Hi I have below dropdown:

from ipywidgets import interact, interactive, fixed, interact_manual 
import ipywidgets as widgets

def f(Books):
    return Books
interact(f, Books=['a','b','c','d']);

This populates a dropdown list allowing user to choose from a, b, c, d.

Let's say user chooses one of the four.

How do you reference the result?

I want to use the output of the dropdown as a variable in other formulas.

ex.

if Books = a:
x = 1+1

what GUI library are you using? (where does `interact` come from?) — Aaron, Jan 13 '20 at 18:31
from ipywidgets import interact, interactive, fixed, interact_manual import ipywidgets as widgets — Michael Yoo, Jan 13 '20 at 18:39

score 2 · Accepted Answer · answered Jan 13 '20 at 18:57

At the risk of recommending something that's generally terrible practice, I'd use a Global variable here. It's quick and easy, and given the interactive / prototyping nature of iPython, a lot of the usual arguments against global variables aren't super important.

Basically, every time you change a variable on the input of the interact widget, f() is called. So you simply must update this variable inside the function:

from ipywidgets import interact, interactive, fixed, interact_manual 
import ipywidgets as widgets

myvar = ''

def f(Books):
    global myvar
    myvar = Books
    return Books

interact(f, Books=['a','b','c','d']);

Python: Interact Dropdown - how to reference the output

1 Answers1