Disallow certain selection combinations in st.multiselect?

[cwerner]

Hi.

I want to prevent the user to make certain combinations in st.multiselect().

I’m not quite sure if this is possible?

Example:

sel_vars = st.empty()
vars = sel_vars.multiselect("Pick one or multiple variables", 
                            ["N2O", "NO","N2","CH4"], 
                            default=["N2O"])

# I want to disallow the user to match CH4 with any
# of the N-based selections since plotting them later in a 
# graph does not make sense (the plot axis is kg N yr-1).

[komodovaran]

This is more of a python solution in general, by simply checking what elements are in the resulting list.

Otherwise the multiselect would have to have these filtering capabilities built in, which I don’t see happening because this could be very complicated to generalized for all cases.

import streamlit as st

def main():
    sel_vars = st.empty()
    vars = sel_vars.multiselect("Pick one or multiple variables",
                                ["N2O", "NO", "N2", "CH4"],
                                default = ["N2O"])
    st.write(vars)

    if "CH4" in vars:
        st.write("CH4 in vars")
        if any([a in vars for a in ("N2O", "NO", "N2")]):
            st.warning("Impossible combination")
            return


if __name__ == "__main__":
    main()

[cwerner]

Of course!

If did not have a main() function in this script and thus could not simply use return .

Thanks!