Streamlit multiselect line chart

Question

I am trying to do charts with multiselect options using Streamlit app. Actually, I only achieve to do a chart with a unique selectbox (no multiple choices).

This is the code below that works with a unique selection:

df = pd.DataFrame(px.data.gapminder())

def plot():

    clist = data['country'].unique()
    country = st.selectbox('Select country', clist)
    st.header('You selected:', country)
    fig = px.line(df[df['country'] == country], x = "year", y = "gdpPercap", title = country)
    st.plotly_chart(fig)

But when I replace st.selectbox by st.multiselect the plot does not work.

Answer 1

You can do it like this:

import pandas as pd
import streamlit as st
import plotly.express as px
import plotly.graph_objects as go


def plot():

    df = pd.DataFrame(px.data.gapminder())

    clist = df["country"].unique().tolist()

    countries = st.multiselect("Select country", clist)
    st.header("You selected: {}".format(", ".join(countries)))

    dfs = {country: df[df["country"] == country] for country in countries}

    fig = go.Figure()
    for country, df in dfs.items():
        fig = fig.add_trace(go.Scatter(x=df["year"], y=df["gdpPercap"], name=country))

    st.plotly_chart(fig)


plot()

using st.multiselect and then add_trace to add every country after the other. The dict dfs is there to map every sub-dataframe for the country for easy access.

It gives the following: