1 1 Multiselect Explained

Key Concepts

• Multiselect Widget: A user interface element that allows users to select multiple options from a list.
• Options List: The list of choices available for selection.
• Default Selection: The initial options that are pre-selected when the widget is loaded.
• Return Value: The list of selected options returned by the widget.

Explanation

1. Multiselect Widget

The st.multiselect widget in Streamlit is used to create a multiselect dropdown menu. This widget allows users to select one or more options from a predefined list. It is particularly useful when users need to make multiple choices, such as selecting multiple items from a list.

2. Options List

The options list is a list of strings that represent the choices available to the user. Each string in the list is a selectable option. The user can select any number of these options from the list.

3. Default Selection

The default selection parameter allows you to specify which options are pre-selected when the widget is first loaded. This can be useful for guiding users to a reasonable starting point or for pre-selecting commonly chosen options.

4. Return Value

The multiselect widget returns a list of the selected options. This list can be used in further computations or displayed to the user. If no options are selected, the returned list will be empty.

Examples

Example 1: Basic Multiselect

import streamlit as st

options = ["Option 1", "Option 2", "Option 3", "Option 4"]
selected_options = st.multiselect("Select options:", options)
st.write(f"You selected: {selected_options}")
    

Example 2: Multiselect with Default Selection

import streamlit as st

options = ["Option 1", "Option 2", "Option 3", "Option 4"]
default_selection = ["Option 2", "Option 4"]
selected_options = st.multiselect("Select options:", options, default=default_selection)
st.write(f"You selected: {selected_options}")
    

Analogies

Think of the multiselect widget as a digital version of a checklist. The user is presented with a list of items, and they can check off multiple items as needed. The default selection is like pre-checking some items on the checklist, making it easier for the user to start.

By mastering the use of st.multiselect, you can create interactive dropdown menus in your Streamlit applications that allow users to make multiple choices. This enhances the user experience by providing flexibility and ease of use.