streamlit

name	streamlit
description	When working with Streamlit web apps, data dashboards, ML/AI app UIs, interactive Python visualizations, or building data science applications with Python

Streamlit Skill

Comprehensive assistance with Streamlit development, generated from official documentation covering 317 pages of content including API reference, tutorials, deployment guides, and best practices.

When to Use This Skill

This skill should be triggered when:

• Building web apps with Python for data science, ML/AI, or analytics
• Creating dashboards with interactive visualizations and real-time data
• Developing data apps that need rapid prototyping and deployment
• Implementing widgets like buttons, sliders, file uploaders, or chat interfaces
• Working with charts using built-in charting or custom visualizations
• Building map visualizations with st.map, st.pydeck_chart, or st.plotly_chart for geographic data
• Deploying apps to Streamlit Community Cloud or other platforms
• Testing Streamlit apps with the app testing framework
• Configuring Streamlit apps with themes, secrets, or custom settings
• Building multi-page apps with navigation and routing
• Integrating authentication with OpenID Connect providers

Key Concepts

Core Architecture

Script-based execution: Streamlit apps run as Python scripts that rerun from top to bottom on every user interaction. This makes development simple but requires understanding state management.

Session State: Persistent data storage across reruns using st.session_state. Essential for maintaining user data, form inputs, and application state.

Caching: Use @st.cache_data for data operations and @st.cache_resource for expensive resources like ML models or database connections.

App Structure

Magic commands: Write variables or strings standalone to display them automatically (when magicEnabled is True).

Widget callbacks: Functions that run when widget values change, useful for complex interactions and state updates.

Fragments: Isolated portions of your app that can rerun independently with @st.fragment, improving performance for partial updates.

Quick Reference

Example 1: Hello World & Basic Display

import streamlit as st

# Simple text display
st.title("My First Streamlit App")
st.header("Welcome to Data Science")
st.write("Hello, World!")

# Magic command (displays automatically)
"This is magic!"

# Display data
import pandas as pd
df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]})
st.dataframe(df)

Example 2: Interactive Widgets & Session State

import streamlit as st

# Initialize session state
if 'count' not in st.session_state:
    st.session_state.count = 0

# Button with callback
def increment():
    st.session_state.count += 1

st.button('Increment', on_click=increment)
st.write(f'Count: {st.session_state.count}')

# Various input widgets
name = st.text_input("Enter your name")
age = st.slider("Select age", 0, 100, 25)
option = st.selectbox("Choose option", ['A', 'B', 'C'])
uploaded_file = st.file_uploader("Upload CSV")

Example 3: Charts & Visualizations

import streamlit as st
import pandas as pd
import numpy as np

# Sample data
data = pd.DataFrame({
    'date': pd.date_range('2024-01-01', periods=30),
    'values': np.random.randn(30).cumsum()
})

# Built-in charts
st.line_chart(data.set_index('date'))
st.area_chart(data.set_index('date'))
st.bar_chart(data.set_index('date'))

# Map visualization
map_data = pd.DataFrame({
    'lat': [37.76, 37.77, 37.78],
    'lon': [-122.4, -122.41, -122.42]
})
st.map(map_data)

Example 4: Map Visualizations (st.map, st.pydeck_chart, st.plotly_chart)

Streamlit provides three powerful approaches for creating interactive map visualizations, each with different capabilities and use cases.

Option 1: st.map() - Simple & Quick Maps

Best for: Basic scatterplot maps with minimal configuration. Auto-centers and auto-zooms to your data.

import streamlit as st
import pandas as pd

# Basic map with latitude/longitude
df = pd.DataFrame({
    'lat': [37.76, 37.77, 37.78],
    'lon': [-122.4, -122.41, -122.42]
})
st.map(df)

# Customized with fixed styling
st.map(df, size=20, color="#0044ff")

# Dynamic sizing and coloring from data columns
df_dynamic = pd.DataFrame({
    'latitude': [37.76, 37.77, 37.78, 37.79],
    'longitude': [-122.4, -122.41, -122.42, -122.43],
    'size_col': [100, 200, 150, 300],  # Size in meters
    'color_col': ['#ff0000', '#00ff00', '#0000ff', '#ffff00']
})
st.map(df_dynamic, 
       latitude='latitude', 
       longitude='longitude',
       size='size_col', 
       color='color_col',
       zoom=11)

Key Features:

• Automatically searches for columns named lat, latitude, LAT, or LATITUDE (same for longitude)
• Uses Carto tiles by default (can configure Mapbox with API key)
• Size parameter in meters (physical ground distance)
• Color accepts hex strings, RGB/RGBA tuples, or column names

Option 2: st.pydeck_chart() - Advanced 3D Visualizations

Best for: Complex visualizations with 3D rendering, multiple layers, and advanced interactivity.

import streamlit as st
import pandas as pd
import pydeck as pdk

# Sample data - network connections between cities
connections = pd.DataFrame({
    'start_lat': [37.7749, 40.7128, 41.8781],
    'start_lon': [-122.4194, -74.0060, -87.6298],
    'end_lat': [34.0522, 29.7604, 33.4484],
    'end_lon': [-118.2437, -95.3698, -112.0740],
})

# Create arc layer for connections
arc_layer = pdk.Layer(
    'ArcLayer',
    data=connections,
    get_source_position='[start_lon, start_lat]',
    get_target_position='[end_lon, end_lat]',
    get_source_color=[255, 0, 0, 160],
    get_target_color=[0, 255, 0, 160],
    auto_highlight=True,
    width_scale=0.0001,
    get_width='outbound',
    width_min_pixels=2,
    pickable=True,
)

# Hub cities as scatterplot
hubs = pd.DataFrame({
    'lat': [37.7749, 40.7128, 41.8781],
    'lon': [-122.4194, -74.0060, -87.6298],
    'name': ['San Francisco', 'New York', 'Chicago'],
    'radius': [30000, 40000, 35000]
})

scatter_layer = pdk.Layer(
    'ScatterplotLayer',
    data=hubs,
    get_position='[lon, lat]',
    get_color='[255, 140, 0]',
    get_radius='radius',
    pickable=True,
)

# Set view state
view_state = pdk.ViewState(
    latitude=37.7749,
    longitude=-95.7129,
    zoom=3,
    pitch=40,
)

# Create deck with multiple layers
deck = pdk.Deck(
    layers=[arc_layer, scatter_layer],
    initial_view_state=view_state,
    tooltip={"text": "{name}"},
    map_style='mapbox://styles/mapbox/light-v9',
)

st.pydeck_chart(deck)

Interactive Selection with PyDeck:

import streamlit as st
import pydeck as pdk
import pandas as pd

# Enable selection
selected = st.pydeck_chart(
    deck,
    on_select="rerun",
    selection_mode="multi-object",
    height=600,
    key="map_selection"
)

# Access selected data
if selected and 'selection' in selected:
    st.write("Selected objects:", selected['selection'])

Key Features:

• Supports multiple layers (ScatterplotLayer, HexagonLayer, ArcLayer, etc.)
• 3D visualizations with pitch and bearing controls
• WebGL-powered for high performance
• Interactive tooltips and selections
• Limitation: Uses 2 WebGL contexts per chart - avoid more than 8 charts per page

Map Tile Providers:

• Default: Carto (set via CARTO_API_KEY environment variable)
• Mapbox: Requires account and API key (map_style='mapbox://styles/...')

Option 3: st.plotly_chart() - Plotly Geographic Charts

Best for: Interactive Plotly charts with geographic projections, including scattergeo and choropleth maps.

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

# Geographic scatterplot
df = pd.DataFrame({
    'city': ['San Francisco', 'New York', 'Chicago', 'Los Angeles'],
    'lat': [37.7749, 40.7128, 41.8781, 34.0522],
    'lon': [-122.4194, -74.0060, -87.6298, -118.2437],
    'population': [883305, 8336817, 2746388, 3979576],
    'state': ['CA', 'NY', 'IL', 'CA']
})

# Scattergeo with geographic projection
fig = px.scatter_geo(
    df,
    lat='lat',
    lon='lon',
    text='city',
    size='population',
    color='state',
    hover_name='city',
    hover_data={'population': ':,'},
    scope='usa',
    title='US City Populations'
)

fig.update_traces(marker=dict(sizemin=5))
fig.update_layout(geo=dict(
    showland=True,
    landcolor='rgb(243, 243, 243)',
    coastlinecolor='rgb(204, 204, 204)',
))

st.plotly_chart(fig, use_container_width=True)

Mapbox Scatter (Modern Approach):

import plotly.express as px

# Note: Mapbox traces are deprecated - use scatter_map instead
fig = px.scatter_map(
    df,
    lat='lat',
    lon='lon',
    size='population',
    color='state',
    hover_name='city',
    zoom=3,
    mapbox_style="open-street-map"
)

st.plotly_chart(fig, theme="streamlit")

Key Features:

• Full Plotly interactivity (hover, zoom, pan)
• Geographic projections (scattergeo) or tile-based (scatter_map)
• Streamlit theme automatically applied (use theme=None for Plotly default)
• For >1000 points, uses WebGL rendering (can force SVG with render_mode="svg")

Important: Mapbox traces are deprecated in favor of Maplibre-based traces (introduced in Plotly.py 5.24+)

Choosing the Right Map Approach

Feature	st.map()	st.pydeck_chart()	st.plotly_chart()
Ease of use	⭐⭐⭐⭐⭐ Simplest	⭐⭐⭐ Moderate	⭐⭐⭐⭐ Easy
3D support	❌ No	✅ Yes	❌ No
Multiple layers	❌ No	✅ Yes	⚠️ Limited
Custom styling	⚠️ Basic	✅ Extensive	✅ Extensive
Selection events	❌ No	✅ Yes	✅ Yes
Best for	Quick demos	Complex networks	Data analysis
Performance	Fast	Very fast (WebGL)	Fast

Map Development Best Practices

Performance:

• Cache geocoding results with @st.cache_data
• For PyDeck, limit to 8 charts per page (WebGL context limits)
• For large datasets (>1000 points), PyDeck typically performs best

Tile Providers:

• Carto: Free, no API key required (default for st.map)
• Mapbox: Requires API key, more style options
• OpenStreetMap: Free, available in Plotly

Common Patterns:

import streamlit as st
import pandas as pd
from geopy.geocoders import Nominatim

# Geocoding with caching
@st.cache_data
def geocode_city(city_name):
    """Convert city name to coordinates"""
    geolocator = Nominatim(user_agent="myapp")
    location = geolocator.geocode(city_name)
    if location:
        return location.latitude, location.longitude
    return None, None

# Network map pattern (like your app1.py)
def create_network_map(hub_city, connected_cities):
    """Create a map showing hub and its connections"""
    # Your map creation logic here
    pass

Session State for Map Interactions:

import streamlit as st

# Track selected location
if 'selected_city' not in st.session_state:
    st.session_state.selected_city = None

# Create interactive map
selected = st.pydeck_chart(
    deck,
    on_select="rerun",
    key="city_selector"
)

if selected:
    st.session_state.selected_city = selected
    st.write(f"Selected: {st.session_state.selected_city}")

Example 5: Layouts & Containers

import streamlit as st

# Columns
col1, col2, col3 = st.columns(3)
with col1:
    st.header("Column 1")
    st.write("Content here")
with col2:
    st.header("Column 2")
    st.button("Click me")
with col3:
    st.header("Column 3")
    st.checkbox("Check me")

# Sidebar
with st.sidebar:
    st.header("Sidebar")
    filter_val = st.slider("Filter", 0, 100)

# Tabs
tab1, tab2 = st.tabs(["Data", "Charts"])
with tab1:
    st.write("Your data here")
with tab2:
    st.line_chart([1, 2, 3, 4, 5])

# Expander
with st.expander("Click to expand"):
    st.write("Hidden content revealed!")

Example 6: Forms & User Input

import streamlit as st

# Form prevents rerun on every input change
with st.form("my_form"):
    st.write("User Registration")
    name = st.text_input("Name")
    email = st.text_input("Email")
    age = st.number_input("Age", min_value=0, max_value=120)

    # Form submit button
    submitted = st.form_submit_button("Submit")
    if submitted:
        st.success(f"Welcome {name}!")
        st.session_state.user_data = {
            'name': name,
            'email': email,
            'age': age
        }

Example 7: Caching for Performance

import streamlit as st
import pandas as pd
import time

# Cache data loading (recomputes when inputs change)
@st.cache_data
def load_data(file_path):
    time.sleep(2)  # Simulate expensive operation
    return pd.read_csv(file_path)

# Cache ML models/resources (persists across reruns)
@st.cache_resource
def load_model():
    from sklearn.ensemble import RandomForestClassifier
    model = RandomForestClassifier()
    # Load trained model...
    return model

# Use cached functions
data = load_data("data.csv")
model = load_model()
st.write(data)

Example 8: Chat Interface (LLM Apps)

import streamlit as st

# Initialize chat history
if "messages" not in st.session_state:
    st.session_state.messages = []

# Display chat messages
for message in st.session_state.messages:
    with st.chat_message(message["role"]):
        st.write(message["content"])

# Chat input
if prompt := st.chat_input("What would you like to know?"):
    # Add user message
    st.session_state.messages.append({"role": "user", "content": prompt})
    with st.chat_message("user"):
        st.write(prompt)

    # Generate and display assistant response
    response = f"Echo: {prompt}"  # Replace with actual LLM call
    st.session_state.messages.append({"role": "assistant", "content": response})
    with st.chat_message("assistant"):
        st.write(response)

Example 9: App Testing with pytest

# app.py
import streamlit as st

st.session_state.beans = st.session_state.get("beans", 0)
st.title("Bean counter")
addend = st.number_input("Beans to add", 0, 10)
if st.button("Add"):
    st.session_state.beans += addend
st.markdown(f"Beans counted: {st.session_state.beans}")

# tests/test_app.py
from streamlit.testing.v1 import AppTest

def test_increment_and_add():
    """Test that incrementing and adding works"""
    at = AppTest.from_file("app.py").run()
    at.number_input[0].increment().run()
    at.button[0].click().run()
    assert at.markdown[0].value == "Beans counted: 1"

Example 10: User Authentication (OpenID Connect)

import streamlit as st

# Check authentication status
if not st.user.is_logged_in:
    if st.button("Log in"):
        st.login()
else:
    st.write(f"Hello, {st.user.name}!")
    st.write(f"Email: {st.user.email}")

    if st.button("Log out"):
        st.logout()

# Configuration in .streamlit/secrets.toml:
# [auth]
# redirect_uri = "http://localhost:8501/oauth2callback"
# cookie_secret = "your-secret-key"
# client_id = "your-client-id"
# client_secret = "your-client-secret"
# server_metadata_url = "https://accounts.google.com/.well-known/openid-configuration"

Example 11: Configuration & Theming

# .streamlit/config.toml

[theme]
primaryColor = "#F63366"
backgroundColor = "#FFFFFF"
secondaryBackgroundColor = "#F0F2F6"
textColor = "#262730"
font = "sans-serif"

[server]
port = 8501
enableCORS = false
maxUploadSize = 200

[client]
showErrorDetails = true
toolbarMode = "auto"

Reference Files

This skill includes comprehensive documentation organized into focused categories:

api.md (439KB, 187 pages)

Complete API reference covering all Streamlit commands:

• Display elements: st.write, st.markdown, st.title, st.header, st.text, st.code, st.latex
• Data display: st.dataframe, st.table, st.metric, st.json, st.data_editor
• Charts: st.line_chart, st.area_chart, st.bar_chart, st.map, st.plotly_chart, st.altair_chart
• Input widgets: st.button, st.checkbox, st.radio, st.selectbox, st.slider, st.text_input, st.file_uploader
• Media: st.image, st.audio, st.video, st.camera_input
• Layouts: st.columns, st.tabs, st.expander, st.container, st.sidebar
• Chat elements: st.chat_message, st.chat_input
• Status elements: st.progress, st.spinner, st.success, st.error, st.warning
• Control flow: st.stop, st.rerun, st.form, st.dialog, @st.fragment
• State: st.session_state, st.query_params
• Caching: @st.cache_data, @st.cache_resource
• Connections: st.connection, database integrations
• User auth: st.login, st.logout, st.user
• Configuration: st.set_page_config, config.toml options

tutorials.md (111KB, 57 pages)

Step-by-step guides and practical examples:

• Getting started tutorials: Creating your first app, multi-page apps
• LLM/Chat apps: Building conversational interfaces, chat response feedback
• Database connections: AWS S3, BigQuery, MongoDB, PostgreSQL, Snowflake, TigerGraph
• Data handling: Dataframe row selections, working with large datasets
• Execution flow: Fragments, forms, multipage navigation
• Authentication: Google, Microsoft OAuth integration
• Configuration: Theming, fonts, static file serving

concepts.md (103KB, 42 pages)

Deep dives into Streamlit architecture and advanced concepts:

• Architecture: How Streamlit runs, script execution model, app lifecycle
• Caching: @st.cache_data vs @st.cache_resource, cache invalidation
• Session State: Managing state across reruns, widget semantics
• Multi-page apps: Pages directory structure, navigation, dynamic routing
• Fragments: Partial reruns for performance optimization
• Forms: Batching user input to prevent excessive reruns
• App testing: AppTest framework, simulating user interactions
• Custom components: Creating reusable UI components
• Configuration: Environment variables, config.toml structure
• Design patterns: Threading, custom classes, timezone handling

deployment.md (77KB, 22 pages)

Comprehensive deployment and hosting guidance:

• Streamlit Community Cloud: GitHub integration, workspace management, app settings
• Deployment from templates: Quick start guides
• App dependencies: requirements.txt, packages.txt, managing secrets
• Secrets management: secrets.toml, environment variables
• Docker deployment: Containerization best practices
• Kubernetes: Scaling and orchestration
• Snowflake: Deploying Streamlit in Snowflake
• App analytics: Monitoring usage and performance
• SEO & indexability: Optimizing for search engines
• Status & troubleshooting: Common deployment issues

getting_started.md (65KB, 26 pages)

Beginner-friendly introduction to Streamlit:

• Installation: Command line, Anaconda, Streamlit Playground
• Main concepts: Script execution, data flow, widgets
• Advanced concepts: Session state, caching, performance
• Summary & next steps: Roadmap for learning

knowledge_base.md (21KB, 48 pages)

Common questions, troubleshooting, and solutions:

• Using Streamlit: Widget behavior, file uploads, downloading data, serialization
• Dependencies: Module installation, package management, common errors
• Deployment issues: Authentication, resource limits, remote start, WSGI protocol
• Best practices: Sanity checks, supported browsers, camera access

other.md (2.2KB)

Miscellaneous topics and utilities not fitting other categories

Working with This Skill

For Beginners

1. Start here: Read getting_started.md for foundational concepts
2. First app: Follow the "Hello World" example in Quick Reference #1
3. Learn widgets: Review Quick Reference #2 for interactive elements
4. Understand state: Study Session State in Quick Reference #2 and concepts.md

For Intermediate Users

1. Performance: Master caching (Quick Reference #6, concepts.md)
2. Layouts: Build complex UIs with columns, tabs, sidebars (Quick Reference #4)
3. Charts: Create visualizations (Quick Reference #3, api.md)
4. Multi-page apps: Structure larger applications (concepts.md, tutorials.md)
5. Testing: Write tests for your apps (Quick Reference #8, concepts.md)

For Advanced Users

1. Fragments: Optimize with partial reruns (concepts.md)
2. Custom components: Extend Streamlit's capabilities (concepts.md)
3. Authentication: Implement user login (Quick Reference #9, tutorials.md)
4. Deployment: Scale to production (deployment.md)
5. Database integration: Connect to data sources (tutorials.md, api.md)

Navigation Tips

• Need a specific widget? Search api.md for st.<widget_name>
• Error troubleshooting? Check knowledge_base.md first
• Deployment issues? Consult deployment.md
• Understanding how Streamlit works? Read concepts.md architecture section
• Building something specific? Check tutorials.md for similar examples

Best Practices

Performance

• Use @st.cache_data for data loading and transformations
• Use @st.cache_resource for ML models and database connections
• Implement @st.fragment for partial updates in large apps
• Minimize work in the main script body; push to cached functions

State Management

• Initialize session state at the top of your script
• Use widget key parameter to sync with session state
• Avoid putting non-serializable objects in session state

UI/UX

• Use st.form to batch related inputs and reduce reruns
• Provide clear labels and help text for widgets
• Use status indicators (st.progress, st.spinner) for long operations
• Structure layouts with columns and containers for responsive design

Development

• Test your apps with the AppTest framework
• Use .streamlit/config.toml for local configuration
• Keep secrets in .streamlit/secrets.toml (never commit to git)
• Enable runOnSave in config for auto-reload during development

Common Patterns

Data App Template

import streamlit as st
import pandas as pd

# Page config
st.set_page_config(page_title="My Data App", layout="wide")

# Load data (cached)
@st.cache_data
def load_data():
    return pd.read_csv("data.csv")

# Sidebar filters
with st.sidebar:
    st.header("Filters")
    category = st.selectbox("Category", options=['All', 'A', 'B', 'C'])

# Main content
st.title("My Data App")
data = load_data()

# Apply filters
if category != 'All':
    data = data[data['category'] == category]

# Display
col1, col2 = st.columns(2)
with col1:
    st.dataframe(data)
with col2:
    st.line_chart(data.set_index('date'))

LLM Chat App Template

See Quick Reference Example 8 for complete chat interface implementation.

Resources

• Official Docs: https://docs.streamlit.io
• Community Forum: https://discuss.streamlit.io
• GitHub: https://github.com/streamlit/streamlit
• Gallery: https://streamlit.io/gallery
• Cheat Sheet: https://docs.streamlit.io/develop/quick-reference/cheat-sheet

Notes

• This skill was automatically generated from 317 pages of official Streamlit documentation
• All code examples are extracted from official docs and tested patterns
• Reference files preserve structure and links to source documentation
• Last updated: Based on Streamlit documentation as of October 2025