Trying to Develop Visited Countries Colored Map Generation App with Streamlit

import os
import json

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


COUNTRY_DATA = 'data/countries.json'
WORLD_HERITAGE_DATA = 'data/world_heritages.json'


def on_change_uploaded_file():
    st.session_state['need_rerun'] = True


def on_change_uploaded_file2():
    st.session_state['need_rerun2'] = True


def main():
    # Load country data
    countries = None
    with open(COUNTRY_DATA) as f:
        countries = json.load(f)

    country_list = [c['name_en'] for c in countries]
    default_visited_country = ['Japan']
    if 'default_visited_country' in st.session_state:
        default_visited_country = st.session_state['default_visited_country']

    name_alpha3_dict = {}
    for c in countries:
        name_alpha3_dict[c['name_en']] = c['alpha3']

    # Load world heritage data
    # Skip

    # UI
    st.title('訪れた国・世界遺産')
    st.write('訪れたことがある国や世界遺産を地図にプロットして可視化するサイトです。')
    st.write('どこを訪れたのか見返したい時に利用してください。')

    tab1, tab2 = st.tabs(["国", "世界遺産"])

    with tab1:
        st.write('### これまでに訪れた国はどこですか？')
        options = st.multiselect(
            '国名のリストから選択してください。',
            country_list,
            default_visited_country)
        uploaded_file = st.file_uploader("選択した国一覧の内容をダウンロードしたファイルからでも選択いただけます。",
                                         key='country',
                                         on_change=on_change_uploaded_file)
        uploaded_countries = None
        if uploaded_file is not None:
            uploaded_countries = json.load(uploaded_file)

        data = dict(country=[], country_code=[], number_of_visited=[])
        for c in options:
            data['country'].append(c)
            data['country_code'].append(name_alpha3_dict[c])
            data['number_of_visited'].append(1)
        if uploaded_countries is not None:
            for c in uploaded_countries:
                if c in name_alpha3_dict and c not in options:
                    data['country'].append(c)
                    data['country_code'].append(name_alpha3_dict[c])
                    data['number_of_visited'].append(1)
                    options.append(c)
        st.session_state['default_visited_country'] = options
        df = pd.DataFrame(data=data)

        st.write('### 選択した国一覧')
        st.download_button('Download', json.dumps(options), file_name='visited_countries.json')
        st.write(options)

        if 'need_rerun' in st.session_state and st.session_state['need_rerun']:
            st.session_state['need_rerun'] = False
            raise st.experimental_rerun()

        fig = px.choropleth(df,
                            locations='country_code',
                            hover_name='country')

        st.write('### 世界地図')
        st.write('地図にカーソルを合わせると表示されるカメラアイコンから画像を保存できます。また、左上右下の 2 方向の矢印のアイコンから拡大できます。')
        st.plotly_chart(fig, theme="streamlit", use_container_width=True)

    with tab2:
        # Skip


if __name__ == '__main__':
    main()