Select#

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import panel as pn
pn.extension()

The Select widget allows selecting a value from a list or dictionary of options by selecting it from a dropdown menu or selection area. It falls into the broad category of single-value, option-selection widgets that provide a compatible API and include the RadioBoxGroup, AutocompleteInput and DiscreteSlider widgets.


Discover more on using widgets to add interactivity to your applications in the how-to guides on interactivity. Alternatively, learn how to set up callbacks and (JS-)links between parameters or how to use them as part of declarative UIs with Param.




Parameters:#


For details on other options for customizing the component see the layout and styling how-to guides.




Core#


    

  • options (list or dict): A list or dictionary of options to select from
    • 

  • disabled_options (list): Optional list of options that are disabled, i.e. unusable and un-clickable. If options is a dictionary the list items must be dictionary values.
    • 

  • groups (dict): A dictionary whose keys are used to visually group the options and whose values are either a list or a dictionary of options to select from. Mutually exclusive with options and valid only if size is 1.
    • 

  • size (int, default=1): Declares how many options are displayed at the same time. If set to 1 displays options as dropdown otherwise displays scrollable area.
    • 

  • value (object): The current value; must be one of the option values
    • 







Display#


    

  • disabled (boolean): Whether the widget is editable
    • 

  • name (str): The title of the widget
    • 





select = pn.widgets.Select(name='Select', options=['Biology', 'Chemistry', 'Physics'])

select








Like most other widgets, Select has a value parameter that can be accessed or set:


select.value





Biology


The options parameter also accepts a dictionary whose keys are going to be the labels of the dropdown menu.


select = pn.widgets.Select(name='Select', options={'Biology': 1, 'Chemistry': 2})

select








select.value





1


Updating the value will display the right label.


select.value = 2





A subset of the displayed items can be disabled with disabled_options. The widget value cannot be set to one of the disabled_options, either programmatrically or with the user interface.


select = pn.widgets.Select(name='Select', options=['Biology', 'Chemistry', 'Physics'], disabled_options=['Chemistry'])

select








The items displayed in the dropdown menu can be grouped visually (also known as optgroup) by setting the groups parameter instead of options. groups accepts a dictionary whose keys are used to group the options and whose values are defined similarly to how options are defined.


select = pn.widgets.Select(name='Select', groups={'Europe': ['Greece', 'France'], 'Africa': ['Algeria', 'Congo']})

select








select.value





Greece


Instead of a dropdown menu we can also select one option from a list by rendering multiple options at once using the size parameter:


select_area = pn.widgets.Select(name='Select', options=['Biology', 'Chemistry', 'Physics'], size=2)

select_area








When size is set to a value greater than 1 the widget supports the disabled_options parameter but does not support groups.


pn.widgets.Select(name='Select', options=['Biology', 'Chemistry', 'Physics'], size=2, disabled_options=['Chemistry'])














Controls#


The Select widget exposes a number of options which can be changed from both Python and Javascript. Try out the effect of these parameters interactively:


pn.Row(select.controls(jslink=True), select)










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