import panel as pn
pn.extension()

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

select

select.value

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

select

select.value

select.value = 2

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

select

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

select

select.value

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

select_area

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

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