Streamlit

1.55.0 · active · verified Sat Mar 28

Streamlit is an open-source Python library that empowers developers to build and share interactive web applications for data science and machine learning with minimal code. It allows transforming Python scripts into beautiful, interactive apps in minutes, supporting various data libraries and visualizations. The current stable version is 1.55.0, with a regular release cadence bringing new features and improvements.

Warnings

gotcha Streamlit's reactive model reruns the entire script from top to bottom on every user interaction or code change. Be mindful of expensive operations and use `st.cache_data` or `st.cache_resource` to memoize functions and prevent unnecessary re-execution. Not using caching for heavy computations can lead to slow app performance.
Fix: Decorate functions with `@st.cache_data` for data-related computations or `@st.cache_resource` for resources like ML models, especially for functions that perform heavy calculations or data loading.
breaking The `st.experimental_user` command has been removed. Access to user information might require alternative authentication methods or specific deployment configurations.
Fix: Refactor authentication flows. For deployed apps, consider Streamlit Community Cloud's authentication features or custom solutions using `st.secrets` with external auth providers.
deprecated The `add_rows` command, used with `st.dataframe` or `st.table`, has been deprecated. While it may still function, its use is discouraged and it will eventually be removed.
Fix: To update data in `st.dataframe` or `st.table`, re-assign the full, updated DataFrame to the component. Streamlit's diffing algorithm will efficiently update the display.
gotcha Widgets within `st.form` only submit their values and trigger a rerun when the `st.form_submit_button` is clicked. If you need immediate interaction, place widgets outside of a form. Also, `st.button` and `st.download_button` cannot be placed inside `st.form`.
Fix: Design your app layout carefully, using `st.form` for batch inputs and direct `st.` calls for immediate interactivity. Do not put `st.button` or `st.download_button` inside a form. If a widget inside a form needs to trigger an immediate action, consider refactoring the logic or placing that specific widget outside the form.
deprecated `kwargs` support for `st.vega_lite_chart` is deprecated. Configurations should be passed via explicit parameters rather than keyword arguments.
Fix: Update your `st.vega_lite_chart` calls to pass chart configurations using dedicated parameters as specified in the Streamlit API reference for `st.vega_lite_chart`.

Install

pip install streamlit Install latest version

Imports

streamlit
```
import streamlit as st
```
The conventional and recommended import alias is `st` for brevity and consistency across Streamlit applications.

Quickstart

This simple Streamlit app demonstrates how to create a title, a text input widget, and a slider. When a user interacts with a widget, Streamlit automatically reruns the script from top to bottom, updating the displayed output.

import streamlit as st

st.title('My First Streamlit App')

name = st.text_input('What is your name?')

if name:
    st.write(f'Hello, {name}!')

number = st.slider('Choose a number', 0, 100, 50)
st.write(f'The number is {number}')

# To run this app, save it as a .py file (e.g., app.py) and run `streamlit run app.py` in your terminal.

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