Hi @vivian,
First welcome back* to the Streamlit community!
When creating a question we recommend you follow these guidelines to help you create a question that is more likely to get an answer:
So the st.multiselect
does not need to have a default value, but st.selectbox
does. Check out our docs on each of these to know how to pass all of the possible parameters to the widgets:
Here is a code example:
import streamlit as st
select = st.selectbox("A selectbox", ["A", 'B', "C"], 0)
multi = st.multiselect("A multiselect", ["A", 'B', "C"])
Happy Streamlit-ing!
Marisa