Programmatically update widgets?

Widgets
1

I’m writing something where I sometimes need to programmatically change the value of widgets. Sample code:

# Update single widgets without triggering callbacks
widget.unobserve_all()
widget.value = new_value # doesn't work for dropdowns???
widget.index = widget.options.index(param_value) # works for dropdowns
widget.send_state() # irrelevant??
widget.observe(lambda change, n=param_name:

I expected widget.value to successfully change the value of the widget - both internally and in the display. But only changing the index actually works. Does this mean there is a different way to programmatically change the value for every kind of widget? Is there a central way to do this that will work the same way for all widgets?

Thanks for any help!

2

Your code does not work at all so nobody knows what you are trying to achieve and where the widget module comes from.

I don’t use widgets much but the most basic example i can give you using ipywidgets looks like this:

import ipywidgets

def i_am_function(name_me_pls):
    return "Hello " + name_me_pls + "!"

ipywidgets.interact(i_am_function, name_me_pls="landoskape")

Other widgets can be invoked by changing the second paramer of the interact call.
A bool gives a checkbox and numbers a slider (start, end, stepsize).

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3

I was being silly and didn’t realize that unobserve_all will prevent the widget.value = new_value from updating the GUI. It’s more selective with what it unobserves and now it works.

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4

That’s an excellent example of a MWE. Apologies for not providing one. I figured out what was going wrong (unobserve_all also unobserves internal callbacks, so removing that line allows me to update the widget value). Thanks for your help.

1 Like