import streamlit as st
import altair as alt
import pandas as pd

# Generate random data for the chart
data = pd.DataFrame({
    'Category': ['A', 'B', 'C', 'D', 'E'],
    'Value': [0.2, 0.5, 0.8, 1.2, 1.5]
})

# Define the color scale for the bars
color_scale = alt.Scale(
    domain=[0, 1],  # Values between 0 and 1 will be blue
    range=['steelblue', 'lightgray']
)

# Create the bar chart using Altair
chart = alt.Chart(data).mark_bar().encode(
    x='Category',
    y='Value',
    color=alt.Color('Value', scale=color_scale)
)

# Render the chart using Streamlit
st.altair_chart(chart, use_container_width=True)