Visualizer #1 | Streamlit

Introduction

• Get started with Streamlit - Streamlit Docs
  • Basic Concepts
  • Advanced Concepts
  • Additional Streamlit features

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1. Basic Concepts

• First you sprinkle a few Streamlit commands into a normal Python script, then you run it with streamlit run
• The app is your canvas, where you’ll draw charts, text, widgets, tables, and more.

1.2 Data Flow

• Streamlit apps have a unique data flow: any time something must be updated on the screen, Streamlit reruns your entire Python script from top to bottom.
  • Whenever you modify your app’s source code.
  • Whenever a user interacts with widgets in the app

1.3 Display and style data

•  You can pass almost anything to st.write(): text, data, Matplotlib figures, Altair charts, and more.

1.4 Widgets

• When you’ve got the data or model into the state that you want to explore, you can add in widgets like st.slider(),st.button() or st.selectbox().

1.5 Layout

• Streamlit makes it easy to organize your widgets in a left panel sidebar with st.sidebar.

• st.columns lets you place widgets side-by-side, and st.expander lets you conserve space by hiding away large content.

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2. Advanced Concepts

• Now that you know how a Streamlit app runs and handles data, let’s talk about being efficient.
  • Caching allows you to save the output of a function so you can skip over it on rerun.
  • Session State lets you save information for each user that is preserved between reruns.

2.1 Caching

• The basic idea behind caching is to store the results of expensive function calls and return the cached result when the same inputs occur again. This avoids repeated execution of a function with the same input values.
  • st.cache_data is the recommended way to cache computations that return data.
  • st.cache_resource is the recommended way to cache global resources like ML models or database connections.

2.2 Session State

• Session State provides a dictionary-like interface where you can save information that is preserved between script reruns.

2.3 Connections

• st.connection takes care of the caching for you so you can enjoy fewer lines of code.

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3. Additional Streamlit Features

• Here’s a quick look at some extra features to take your app to the next level.

3.1 Theming

• Streamlit supports Light and Dark themes out of the box.

• Streamlit will first check if the user viewing an app has a Light or Dark mode preference set by their operating system and browser. If so, then that preference will be used.

3.2 Pages

• As apps grow large, it becomes useful to organize them into multiple pages.

• Streamlit provides a frictionless way to create multipage apps.

  • simply add new .py files in pages folder likepages/page1.py