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.
For details on other options for customizing the component see the layout and styling how-to guides.
options (list or dict): A list or dictionary of options to select fromdisabled_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 valuesdisabled (boolean): Whether the widget is editablename (str): The title of the widgetselect = 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
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
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
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'])
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)