pages/7_CoWIN.py

import streamlit as st
import requests
import json
import pandas as pd
import folium
from streamlit_folium import st_folium
import plotly.graph_objects as go
import numpy as np
from datetime import datetime
from branca.colormap import LinearColormap
import pytz

st.set_page_config(layout="wide", page_title="Real-Time CoWIN Weather Data Dashboard")

@st.cache_data(ttl=300)  # Cache data for 5 minutes (300 seconds)
def fetch_data():
    hk_tz = pytz.timezone('Asia/Hong_Kong')
    current_time = datetime.now(hk_tz).strftime('%Y-%m-%dT%H:%M:%S')
    url = f'https://cowin.hku.hk/API/data/CoWIN/map?time={current_time}'
    response = requests.get(url)
    return json.loads(response.text), current_time

data, fetched_time = fetch_data()

features = data
df = pd.json_normalize(features)

df.rename(columns={
    'station': 'Station',
    'temp': 'Temperature',
    'lat': 'Latitude',
    'lon': 'Longitude',
    'wd': 'Wind Direction',
    'ws': 'Wind Speed',
    'rh': 'Relative Humidity',
    'uv': 'UV Radiation',
    'me_name': 'Name'
}, inplace=True)

attribute = st.selectbox(
    'Select Weather Attributes to Plot and Map (Data from HKO-HKU CoWIN)',
    ['Temperature', 'Wind Speed', 'Relative Humidity', 'UV Radiation']
)

col1, col2, col3 = st.columns([1.65, 2, 1.2])

with col1:
    attr_series = pd.Series(df[attribute].dropna())

    hist_data = np.histogram(attr_series, bins=10)
    bin_edges = hist_data[1]
    counts = hist_data[0]

    def get_color(value, min_value, max_value):
        ratio = (value - min_value) / (max_value - min_value)
        r = int(255 * ratio)
        b = int(255 * (1 - ratio))
        return f'rgb({r}, 0, {b})'

    fig = go.Figure()

    for i in range(len(bin_edges) - 1):
        bin_center = (bin_edges[i] + bin_edges[i + 1]) / 2
        color = get_color(bin_center, bin_edges.min(), bin_edges.max())
        fig.add_trace(go.Bar(
            x=[f'{bin_edges[i]:.1f} - {bin_edges[i + 1]:.1f}'],
            y=[counts[i]],
            marker_color=color,
            name=f'{bin_edges[i]:.1f} - {bin_edges[i + 1]:.1f}'
        ))

    fig.update_layout(
        xaxis_title=f'{attribute}',
        yaxis_title='Count',
        title=f'{attribute} Distribution',
        bargap=0.2,
        title_font_size=20,
        xaxis_title_font_size=14,
        yaxis_title_font_size=14,
        height=350,
        xaxis=dict(title_font_size=14),
        yaxis=dict(title_font_size=14)
    )

    st.plotly_chart(fig, use_container_width=True)
    st.caption(f"Data fetched at: {fetched_time}")

    with st.container():
        col_1, col_2 = st.columns([1, 1])
        with col_1:
            if attr_series.size > 0:
                avg_attr = np.mean(attr_series)
                std_attr = np.std(attr_series)
                max_attr = np.max(attr_series)
                min_attr = np.min(attr_series)

                st.metric(label=f"Average {attribute}", value=f"{avg_attr:.2f}")
                st.metric(label=f"Minimum {attribute}", value=f"{min_attr:.2f}")
        with col_2:
            st.metric(label=f"Maximum {attribute}", value=f"{max_attr:.2f}")
            st.metric(label=f"Std. Dev {attribute}", value=f"{std_attr:.2f}")

def attribute_to_color(value, min_value, max_value):
    """Convert a value to a color based on the gradient."""
    ratio = (value - min_value) / (max_value - min_value)
    return LinearColormap(['blue', 'purple', 'red']).rgb_hex_str(ratio)

with col2:
    m = folium.Map(location=[22.3547, 114.1483], zoom_start=11, tiles='https://landsd.azure-api.net/dev/osm/xyz/basemap/gs/WGS84/tile/{z}/{x}/{y}.png?key=f4d3e21d4fc14954a1d5930d4dde3809',attr="Map infortmation from Lands Department")
    folium.TileLayer(
        tiles='https://mapapi.geodata.gov.hk/gs/api/v1.0.0/xyz/label/hk/en/wgs84/{z}/{x}/{y}.png',
        attr="Map infortmation from Lands Department").add_to(m)

    min_value = df[attribute].min()
    max_value = df[attribute].max()

    for _, row in df.iterrows():
        lat = row['Latitude']
        lon = row['Longitude']
        station = row['Station']
        name = row['Name']
        value = row[attribute]

        color = attribute_to_color(value, min_value, max_value) if pd.notna(value) else 'gray'

        folium.Marker(
            location=[lat, lon],
            popup=(
                f"<p style='font-size: 12px; background-color: white; padding: 5px; border-radius: 5px;'>"
                f"Station: {station}<br>"
                f"Name: {name}<br>"
                f"{attribute}: {value}<br>"
                f"</p>"
            ),
            icon=folium.DivIcon(
                html=f'<div style="font-size: 10pt; color: {color}; padding: 2px; border-radius: 5px;">'
                     f'<strong>{value}</strong></div>'
            )
        ).add_to(m)

    # Create a color scale legend
    colormap = folium.LinearColormap(
        colors=['blue', 'purple', 'red'],
        index=[min_value, (min_value + max_value) / 2, max_value],
        vmin=min_value,
        vmax=max_value,
        caption=f'{attribute}'
    )
    colormap.add_to(m)

    st_folium(m, use_container_width=True , height=650)

with col3:
    st.markdown(
        """
        <style>
        .dataframe-container {
            height: 600px;
            overflow-y: auto;
        }
        </style>
        """,
        unsafe_allow_html=True
    )

    st.dataframe(df[['Station', 'Name', 'Temperature', 'Wind Speed', 'Relative Humidity', 'UV Radiation', 'Latitude', 'Longitude']], height=600)

if st.button("Refresh Data"):
    st.experimental_rerun()

hk_tz = pytz.timezone('Asia/Hong_Kong')
current_time = datetime.now(hk_tz)
if 'last_ran' not in st.session_state or (current_time - st.session_state.last_ran.replace(tzinfo=hk_tz)).total_seconds() > 300:
    st.session_state.last_ran = current_time
    st.experimental_rerun()