Dropdown Selection Explained

Key Concepts

Dropdown selection in Streamlit is facilitated through the st.selectbox() function. This function allows users to select a single option from a list of choices. Understanding how to use st.selectbox() is essential for creating interactive web applications where users need to make choices.

1. st.selectbox()

st.selectbox() is used to create a dropdown menu in Streamlit. It takes two main arguments: the label or prompt for the dropdown, and a list of options from which the user can select. The function returns the selected option, which can then be used in further computations or displayed.

Example:

import streamlit as st

options = ["Option 1", "Option 2", "Option 3"]
selected_option = st.selectbox("Choose an option:", options)
st.write(f"You selected: {selected_option}")
    

In this example, a dropdown menu is created with three options. The user's selection is stored in the variable selected_option, which is then displayed using st.write().

2. Handling User Selection

Once a user makes a selection from the dropdown, you can handle this selection in various ways. For instance, you can use conditional statements to perform different actions based on the selected option. This makes your Streamlit app dynamic and responsive to user input.

Example:

import streamlit as st

options = ["Option 1", "Option 2", "Option 3"]
selected_option = st.selectbox("Choose an option:", options)

if selected_option == "Option 1":
    st.write("You selected Option 1.")
elif selected_option == "Option 2":
    st.write("You selected Option 2.")
else:
    st.write("You selected Option 3.")
    

In this example, different messages are displayed based on the user's selection from the dropdown menu.

Analogies

Think of st.selectbox() as a multiple-choice question in a quiz. The user is presented with a list of options, and they must choose one. The selected option can then be used to determine the next step, similar to how a quiz question leads to the next part of the quiz based on the answer.

Conclusion

By mastering the use of st.selectbox(), you can create interactive dropdown menus in your Streamlit applications. This allows users to make choices that dynamically affect the content and functionality of your app, making it more engaging and user-friendly.