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

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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

Biology

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

Biology

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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