Streamlit: Keep Fragment Running While the Page Loads

Are you tired of waiting for your Streamlit app to load every time you make a change? Do you want to keep your fragment running while the page loads, ensuring a seamless user experience? Look no further! In this article, we’ll explore the magic of Streamlit and show you how to keep your fragment running while the page loads.

What is Streamlit?

Before we dive into the solution, let’s quickly cover what Streamlit is. Streamlit is a Python library that makes it easy to create and share beautiful, custom web apps for machine learning and data science. With Streamlit, you can create interactive dashboards, perform data visualization, and deploy models in minutes. It’s a game-changer for data scientists and analysts alike.

The Problem: Fragment Reloads on Page Load

One of the most frustrating experiences in Streamlit is when your fragment reloads every time you make a change to your app. This can be particularly annoying when you’re working on a complex project and need to tweak multiple components simultaneously. The constant reloading can be distracting and disrupt your workflow.

The Solution: st.cache and st.spinner

The solution to this problem lies in the clever use of two Streamlit functions: `st.cache` and `st.spinner`. By combining these functions, you can keep your fragment running while the page loads, ensuring a seamless user experience.

st.cache: Caching Your Fragment

`st.cache` is a function that allows you to cache the output of a function or a block of code. This means that when you run your app, Streamlit will store the output of the cached function in memory, so it doesn’t need to re-run every time the page loads.

import streamlit as st

@st.cache
def my_fragment():
    # Your fragment code here
    return "Hello, World!"

In the example above, we’ve decorated the `my_fragment` function with `@st.cache`. This tells Streamlit to cache the output of the function, so it doesn’t need to re-run every time the page loads.

st.spinner: Showing a Loading Spinner

`st.spinner` is a function that displays a loading spinner while your app is loading. This provides a visual cue to the user that the app is loading, making the experience more engaging and interactive.

import streamlit as st

with st.spinner('Loading...'):
    # Your fragment code here
    pass

In the example above, we’ve used `st.spinner` to display a loading spinner while the app is loading. This provides a clear visual cue to the user that the app is loading.

Combining st.cache and st.spinner

Now that we’ve covered `st.cache` and `st.spinner`, let’s combine them to create a seamless user experience. By caching your fragment and displaying a loading spinner, you can keep your fragment running while the page loads.

import streamlit as st

@st.cache
def my_fragment():
    # Your fragment code here
    return "Hello, World!"

with st.spinner('Loading...'):
    result = my_fragment()
    st.write(result)

In the example above, we’ve combined `st.cache` and `st.spinner` to create a seamless user experience. The `my_fragment` function is cached, so it doesn’t need to re-run every time the page loads. Meanwhile, the loading spinner provides a visual cue to the user that the app is loading.

Advanced Techniques: Using st.session_state

While `st.cache` and `st.spinner` are powerful tools, there are times when you need more control over the loading process. That’s where `st.session_state` comes in.

`st.session_state` is a dictionary that stores the state of your app across page loads. By using `st.session_state`, you can store the output of your fragment and reuse it across page loads, eliminating the need for reloading.

import streamlit as st

if 'result' not in st.session_state:
    with st.spinner('Loading...'):
        st.session_state.result = my_fragment()

st.write(st.session_state.result)

In the example above, we’ve used `st.session_state` to store the output of the `my_fragment` function. If the output is not already stored in `st.session_state`, we load the fragment and store the result. Otherwise, we retrieve the result from `st.session_state` and write it to the page.

Best Practices: Optimizing Your App

While `st.cache`, `st.spinner`, and `st.session_state` are powerful tools, they can also introduce performance issues if not used correctly. Here are some best practices to optimize your app:

• Use caching wisely: Caching can improve performance, but it can also lead to stale data. Make sure to use caching judiciously and invalidate the cache when necessary.
• Optimize your fragment: Make sure your fragment is optimized for performance. Use efficient algorithms and data structures to minimize loading times.
• Use loading spinners: Loading spinners provide a visual cue to the user that the app is loading. Use them to improve the user experience.
• Test and iterate: Test your app regularly and iterate on performance optimizations. Use tools like Streamlit’s built-in profiler to identify performance bottlenecks.

Conclusion

In this article, we’ve explored the magic of Streamlit and shown you how to keep your fragment running while the page loads. By combining `st.cache`, `st.spinner`, and `st.session_state`, you can create a seamless user experience that delights and engages. Remember to optimize your app using best practices, and don’t be afraid to experiment and try new things. Happy coding!

Function	Description
st.cache	Caches the output of a function or block of code
st.spinner	Displays a loading spinner while the app is loading
st.session_state	Stores the state of the app across page loads

By following the instructions in this article, you’ll be able to create Streamlit apps that are fast, interactive, and engaging. Remember to keep your fragment running while the page loads, and don’t hesitate to reach out if you have any questions or need further assistance.

FAQs

1. Q: How do I cache my entire app?
   A: You can use `st.cache` to cache your entire app by decorating the main function of your app.
2. Q: Can I use st.cache with st.session_state?
   A: Yes, you can use `st.cache` and `st.session_state` together to create a seamless user experience.
3. Q: How do I invalidate the cache?
   A: You can invalidate the cache by using the `st.cache_clear` function or by modifying the input to the cached function.

I hope you found this article helpful! If you have any further questions or need assistance, don’t hesitate to reach out. Happy coding!

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