Fixing `st.plotly_chart` Deprecation Warnings

Hey there, fellow Streamlit enthusiasts! Ever been building a super cool data app, feeling all productive, only to hit a snag? You're using st.plotly_chart to bring your visualizations to life, perhaps setting a handy width="content" or a specific height, and suddenly, a rather cryptic deprecation warning pops up. You scratch your head, thinking, "But I'm just using documented parameters, why am I getting a warning about kwargs?" If this sounds familiar, you're definitely not alone! This particular st.plotly_chart kwargs deprecation warning has been causing a bit of a stir in the Streamlit community, and it can be quite confusing, especially when you're diligently following the documentation. The good news is, we're here to unravel this mystery together and equip you with the knowledge to not only understand why this warning appears but, more importantly, how to fix it. We'll dive deep into what kwargs are in this context, explore the specific scenario that triggers this warning, and walk through the proper way to configure your Plotly charts in Streamlit, ensuring your applications remain robust, warning-free, and delightful for your users. So, let's roll up our sleeves and get those charts displaying perfectly!

Understanding the st.plotly_chart kwargs Deprecation

Let's kick things off by really understanding this st.plotly_chart kwargs deprecation warning. When you see a "kwargs" warning in Python, it usually refers to keyword arguments. In simple terms, **kwargs allows a function to accept an arbitrary number of keyword arguments. For example, if a function my_func(**kwargs) is called as my_func(apple=1, banana=2), then kwargs inside my_func would be a dictionary {'apple': 1, 'banana': 2}. In the context of Streamlit's st.plotly_chart, previously, you could pass various Plotly configuration options directly as kwargs to the function. This offered a lot of flexibility, but it also made the function signature less explicit and harder to manage, potentially leading to conflicts or unexpected behavior.

The core reason for this kwargs deprecation is a move towards a more structured and explicit way of handling Plotly chart configurations within Streamlit. The Streamlit team wants to make it clear which parameters st.plotly_chart directly handles (like use_container_width or width) and which are truly Plotly-specific configuration options. This separation improves clarity, maintainability, and prevents future potential issues. Instead of scattering various Plotly configuration parameters as general kwargs, Streamlit introduced a dedicated config argument. This config argument is designed to be a dictionary where you pass all your Plotly-specific configuration options, making the code much cleaner and easier to debug. For instance, if you wanted to disable the Plotly mode bar, you would now pass config={'displayModeBar': False} instead of displayModeBar=False directly. This shift aligns with best practices in API design, promoting explicit rather than implicit parameter handling. While this change is ultimately beneficial for the long-term health and stability of Streamlit applications, it can definitely cause a momentary headache for developers who encounter these warnings, especially when using seemingly standard parameters like width="content" which should be explicitly handled by Streamlit. We're striving for a world where your Streamlit app development is smooth, and understanding these underlying changes is key to achieving that. This plotly_chart kwargs deprecation warning is a signal to update your approach to chart customization.

Reproducing the Deprecation Warning with width="content"

Let's get practical and look at the exact scenario that often triggers this st.plotly_chart kwargs deprecation warning. Many developers, myself included, have encountered this issue when trying to set the width of their Plotly charts in Streamlit using the width parameter, especially with the value "content". The width="content" option is incredibly useful as it tells Streamlit to automatically size the chart based on its content, making it responsive and visually appealing without manual pixel adjustments. It's a documented feature, and naturally, one would expect it to work without any fuss or warnings. However, the current behavior, particularly with Streamlit version 1.50.0 (and potentially others), shows that even this seemingly innocent and well-intentioned parameter can trip the deprecation warning mechanism.

Consider the following reproducible code example, which perfectly illustrates the problem:

import plotly.graph_objects as go
import streamlit as st

# Create a simple Plotly figure
fig = go.Figure()
fig.add_trace(go.Barpolar(r=[1], theta=[0], width=[120])) # A simple chart element
fig.update_layout(width=500, height=360) # Layout dimensions within Plotly itself

# Display the Plotly chart in Streamlit, using width="content"
st.plotly_chart(fig, width="content")

When you run this code, despite width being an officially recognized parameter for st.plotly_chart (and width="content" being a valid option), you might see a warning similar to this:

"Variable keyword arguments for st.plotly_chart have been "
"deprecated and will be removed in a future release. Use the "
"config argument instead to specify Plotly configuration "
"options."

This plotly_chart kwargs deprecation warning is confusing because width isn't supposed to be a variable keyword argument; it's a named, documented parameter. The warning message specifically points to "variable keyword arguments," implying that width="content" is being mistakenly interpreted as one of those arbitrary **kwargs that should now go into the config dictionary. This discrepancy between the expected behavior for a documented parameter and the actual warning indicates a specific bug or an oversight in how st.plotly_chart currently processes its arguments internally. It's a classic case of the tool thinking you're doing one thing (passing an unhandled kwarg) when you're actually doing another (using a standard, documented parameter). This scenario highlights the need for a clear understanding of the deprecation and also for a resolution to this specific bug, which can be a source of frustration for developers aiming for clean, warning-free console outputs.

Expected vs. Current Behavior: The width Parameter Conundrum

When working with libraries like Streamlit and Plotly, developers naturally expect documented parameters to function as described, without unexpected warnings or errors. For st.plotly_chart, the width parameter is a prime example. The documentation clearly outlines its purpose: to control the width of the rendered chart within your Streamlit application. Users, therefore, anticipate that when they pass width="content" or a specific pixel value like width=700, Streamlit will handle this parameter gracefully, adjusting the chart's display accordingly, and without generating any console messages. This is the expected behavior—a smooth, predictable interaction with the API that allows developers to focus on their application's logic and design, not on deciphering warnings for standard usage. The whole point of explicitly defined parameters is to abstract away the underlying mechanics and provide a clear interface.

However, the current behavior deviates from this expectation, leading to the st.plotly_chart kwargs deprecation warning. As identified in the issue and related pull requests, the st.plotly_chart function has an internal check: if kwargs: show_deprecation_warning(...). The crucial point here is that for some reason, when width="content" (or other width and height values) is passed, it is being inadvertently caught by this kwargs check. This means that instead of width being recognized and processed as a specific, named argument by st.plotly_chart itself, it's being lumped into the general kwargs dictionary. This is a significant regression from previous versions where these parameters worked silently. The result is a persistent and somewhat misleading plotly_chart kwargs deprecation warning that tells you to "Use the config argument instead to specify Plotly configuration options." This advice is sound for actual Plotly configuration options, but it's confusing when applied to Streamlit's own width parameter. It forces developers to either ignore the warning (which isn't ideal for production apps) or search for workarounds for a seemingly standard feature. This conundrum emphasizes a temporary disconnect between how st.plotly_chart internally processes arguments and how its public API is documented and expected to be used by the community. Addressing this specific interaction is vital for a cleaner developer experience, ensuring that warnings are reserved for truly deprecated patterns, not for correct usage of documented features.

Solutions and Best Practices for st.plotly_chart Configuration

Navigating the landscape of deprecation warnings can feel a bit like walking through a maze, but there are clear paths forward to ensure your Streamlit applications remain robust and future-proof, especially when it comes to configuring your st.plotly_chart visualizations. The primary solution for handling Plotly-specific configuration options is to embrace the config argument. This argument is a dictionary where you can pass a wealth of settings that control the behavior and appearance of your Plotly chart, such as enabling/disabling the mode bar, controlling interactivity, or even setting download options for images. This approach makes your code cleaner and aligns with Streamlit's updated API design, moving away from the more ambiguous kwargs.

For example, if you wanted to disable the Plotly mode bar (the small toolbar that appears when you hover over a chart) and prevent image downloads, your code would look something like this:

import plotly.graph_objects as go
import streamlit as st

fig = go.Figure()
fig.add_trace(go.Scatter(x=[1, 2, 3], y=[1, 3, 2]))

# Use the 'config' argument for Plotly-specific settings
st.plotly_chart(
    fig,
    config={
        'displayModeBar': False,      # Disables the Plotly mode bar
        'displaylogo': False,         # Hides the Plotly logo
        'toImageButtonOptions': {     # Options for image download
            'format': 'svg',
            'filename': 'my_custom_plot',
            'height': 500,
            'width': 700,
            'scale': 1
        }
    }
)

This example demonstrates the power and clarity of the config argument. However, what about the width="content" issue we discussed earlier? This is where things get a little tricky due to the identified bug. Ideally, parameters like width and height for st.plotly_chart should be handled directly by Streamlit, separate from the config argument, as they relate to how Streamlit embeds the chart, not how Plotly draws it internally. The width="content" option, in particular, is a Streamlit-specific instruction. Until this specific bug (where width or height are incorrectly interpreted as kwargs) is fully resolved by the Streamlit team, you might find yourself in a situation where even using width="content" triggers the warning. A temporary workaround, if you must have width="content" functionality and want to avoid the warning, might involve manipulating the figure's layout directly before passing it to st.plotly_chart and relying on Plotly's internal resizing, or accepting the warning for now. However, for static width/height, you can set them within fig.update_layout() or simply pass use_container_width=True (if that doesn't trigger a separate warning related to its own deprecation in favor of width). The general rule of thumb is: if it's a visual or interactive setting within the Plotly chart itself, put it in config. If it's about how Streamlit displays the chart in the app layout, use the direct st.plotly_chart parameters, and report any unexpected warnings for those. Always keep an eye on the official Streamlit documentation for st.plotly_chart and release notes for updates on how these parameters are handled.

Why This Matters for Your Streamlit Apps

Understanding and addressing the st.plotly_chart kwargs deprecation warning isn't just about silencing an annoying message in your console; it's fundamentally about building better, more resilient Streamlit applications. When warnings appear, especially persistent ones related to core components like st.plotly_chart, they serve as important signals. Ignoring them, even if your app "seems" to work, can lead to significant problems down the line. First and foremost, a warning-free console is a hallmark of a clean and professional codebase. It means that every piece of your application is using the recommended APIs and practices. When you're debugging, a clutter of deprecation warnings can obscure genuine error messages or critical information, making it harder to pinpoint real issues when they arise. By resolving these plotly_chart kwargs deprecation issues, you're improving the overall clarity and maintainability of your development environment.

Furthermore, adhering to the latest API standards and deprecation notices is crucial for future-proofing your Streamlit apps. Deprecated features are eventually removed. If your application relies heavily on methods that are no longer supported, a future Streamlit update could break your entire app. By proactively migrating to the config argument for Plotly-specific settings and understanding how Streamlit intends to handle layout parameters like width, you're ensuring that your application will continue to function correctly with newer versions of Streamlit. This saves you significant refactoring time and headaches in the long run. It also allows you to take advantage of new features and performance improvements that come with updated versions. Moreover, adopting these best practices fosters a deeper understanding of how Streamlit and Plotly interact. This knowledge empowers you to create more sophisticated and performant data visualizations. It's about being a thoughtful developer who builds not just for today, but for tomorrow, ensuring that your data narratives are presented through robust, reliable, and continuously functional interactive dashboards. By engaging with these changes, you contribute to the stability and longevity of your projects and the wider Streamlit ecosystem.

Conclusion

Phew! We've covered a lot of ground today, diving deep into the often-perplexing world of the st.plotly_chart kwargs deprecation warning. We’ve explored why these kwargs are being deprecated, how to properly use the config argument for Plotly-specific settings, and even touched upon the specific bug related to width="content" that's currently causing some unexpected warnings. Remember, encountering these warnings isn't a sign of failure; it's an opportunity to refine your code and align it with the latest best practices in Streamlit development. By understanding the underlying reasons and adopting the recommended approaches, you're not just silencing a warning; you're building more robust, maintainable, and future-proof data applications. Keep experimenting, keep building, and always strive for clean, warning-free code. Your users (and your future self!) will thank you for it.

For more in-depth information and to stay updated, make sure to check out the official documentation:

• Streamlit's st.plotly_chart documentation: Learn more about its parameters and usage on the Streamlit Documentation.
• Plotly's Python Graphing Library: Explore the vast capabilities of Plotly charts and their configuration options on the Plotly Documentation.