Streamlit `plotly_chart` Kwargs Deprecation Warning Explained

Are you seeing a pesky st.plotly_chart kwargs deprecation warning pop up in your Streamlit applications? Don't worry, you're not alone, and it's completely normal as Streamlit evolves! This article will dive deep into why this warning appears, what it means for your code, and how you can easily adjust your Streamlit applications to keep them running smoothly and future-proof. We'll explore the changes in st.plotly_chart's parameters, focusing on the transition from use_container_width to the more explicit width and height arguments, and how to properly handle Plotly configuration options without triggering any warnings. Streamlit is all about making data apps easy and fun to build, and understanding these updates ensures you continue to harness its full power. This change, while initially a bit jarring, is a step towards a more robust and predictable API, making your data visualizations even more reliable. We'll walk through the practical steps, provide clear code examples, and share best practices to make this transition as seamless as possible. So, if you're a Streamlit developer dealing with this warning, stick around! You'll find everything you need right here to understand and resolve it, ensuring your interactive dashboards remain top-notch and free of annoying messages. The goal is to keep your development workflow efficient and your applications performing optimally, so let's get rid of those warnings together and make your Streamlit apps shine.

Understanding st.plotly_chart and Its Evolution

The st.plotly_chart function is a core component for anyone building interactive data dashboards with Streamlit, allowing seamless integration of Plotly graphs. For a long time, Streamlit provided simple ways to control the layout of these charts, including the convenient use_container_width parameter. This parameter was a fan favorite because it automatically made your Plotly charts expand to fit the full width of their parent container, which is incredibly useful for responsive design and ensuring your visualizations look great on any screen size. However, as frameworks grow and mature, sometimes initial implementations need refining to ensure greater clarity, consistency, and flexibility. The evolution of st.plotly_chart has seen a shift from a more implicit control over chart dimensions, like the Boolean use_container_width, to more explicit width and height arguments, which are now the recommended way to manage your chart's size. This change is part of Streamlit's ongoing commitment to provide a robust and easy-to-use API for developers, making it simpler to specify exactly how you want your charts to behave visually. The old use_container_width was a **kwargs parameter under the hood, meaning it was caught by a general mechanism that handles extra keyword arguments. When Streamlit's developers decided to deprecate general **kwargs for configuration options, use_container_width naturally got swept up in that change. This move encourages developers to use dedicated, well-documented parameters instead of relying on catch-all keyword arguments, leading to cleaner code and fewer unexpected behaviors. The new approach gives you more granular control, allowing you to set specific pixel width and height values or use responsive strings like "content" (which behaves similarly to the old use_container_width but through a dedicated, explicit parameter). This improves readability and maintainability, as the intent of the parameters becomes much clearer at a glance. It’s all about making your Streamlit experience even better by providing clearer pathways for effective application development, reducing ambiguity and promoting more standardized coding practices. By embracing these updates, you're ensuring your applications are aligned with the latest and greatest Streamlit features, making them more resilient to future changes and easier for others to understand and contribute to. This evolutionary step is typical for popular open-source libraries that continuously strive to improve their developer experience.

Diving into the Deprecation Warning: What It Means for You

The st.plotly_chart kwargs deprecation warning is exactly what it sounds like: a heads-up that a way of passing arguments to st.plotly_chart is becoming outdated and will eventually be removed. Specifically, the warning states, "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 message is triggered when you use any keyword argument that isn't explicitly defined as a direct parameter of st.plotly_chart but is instead caught by a generic **kwargs mechanism. A common scenario where users encounter this is when they were previously using use_container_width=True or height="content". While these seem like explicit, documented parameters, they were internally handled via **kwargs in older versions. The core of the issue stems from a change in how Streamlit processes additional keyword arguments passed to st.plotly_chart. Previously, many options, including styling and layout directives like width or height (when set to specific responsive strings like "content"), were passed through a catch-all **kwargs argument. This approach can sometimes lead to ambiguity and makes it harder for the Streamlit team to introduce new features or deprecate old ones without breaking existing code. To combat this and create a clearer, more maintainable API, Streamlit is now encouraging developers to use dedicated parameters for styling (width, height) and a specific config dictionary for Plotly's own configuration options. The width="content" example perfectly illustrates this. Even though width is now a direct, documented argument, if you were using it in a way that used to be part of the **kwargs set, or if the internal parsing still flags it as such due to the transition, the warning might appear. It's a signal that Streamlit wants you to update your syntax to align with the more explicit parameter handling. This ensures that the arguments you pass are correctly interpreted and do not get conflated with Plotly's internal config options. Essentially, this change is about tightening up the API. Instead of having a loose bag of **kwargs that might include anything from chart dimensions to Plotly interactivity settings, Streamlit now wants you to clearly separate these concerns. Dimensions (width, height) go into the specific st.plotly_chart arguments, and all other Plotly-specific configuration (like displayModeBar, scrollZoom, etc.) should be encapsulated within the config dictionary parameter. This not only makes your code more explicit but also significantly reduces the chance of unexpected behavior as Streamlit continues to evolve. Ignoring this warning won't immediately break your app, but it means your code relies on a deprecated feature, which will stop working in a future release, potentially causing your application to fail unexpectedly. Therefore, it's always best to address these warnings promptly to ensure the longevity and stability of your Streamlit projects.

Practical Implications and How to Adapt Your Code

The practical implication of this st.plotly_chart kwargs deprecation warning is straightforward: you need to adjust how you pass certain layout and configuration options to your st.plotly_chart calls. The primary change involves moving away from keyword arguments that are now considered deprecated and adopting the new, explicit parameters. Let's look at the common culprits and their solutions. The most frequent trigger for this warning, as highlighted in the issue, is using width="content" (or height="content"). This was a convenient way to make your Plotly chart fill its container, mimicking use_container_width. The good news is that the solution is incredibly simple because width and height are now first-class arguments to st.plotly_chart. So, if you were writing st.plotly_chart(fig, width="content"), this exact syntax should now be the correct and warning-free way to do it. The warning appears due to an internal deprecation mechanism that might still flag width as a **kwargs argument during the transition phase, even though it's officially supported. The fix, therefore, is often just to ensure you are on the latest stable version of Streamlit. If you are on an older version where width="content" was still being processed via **kwargs, an upgrade will resolve it. However, if the warning persists, it might indicate other **kwargs are being passed. For any other Plotly configuration options that you might have been passing as keyword arguments (e.g., displayModeBar=False, scrollZoom=True), these should now be consolidated into the config dictionary. For instance, if you previously had something like st.plotly_chart(fig, displayModeBar=False, editable=True), you would now write: st.plotly_chart(fig, config={'displayModeBar': False, 'editable': True}). This config dictionary is a powerful way to customize the interactive behavior of your Plotly charts, and housing these options within it makes your code cleaner and clearly distinguishes between Streamlit-specific parameters and Plotly-specific configurations. Remember, Streamlit's own width and height parameters directly control the embedding size of the chart within the Streamlit app, whereas Plotly's internal layout options (which can be passed via fig.update_layout() or the config dictionary) control the plot area within that embedding. Understanding this distinction is key to effectively adapting your code. Always refer to the official Streamlit documentation for the most up-to-date list of parameters for st.plotly_chart to ensure you're using the correct syntax and avoiding deprecated **kwargs. Upgrading your Streamlit version is often the first and most effective step, followed by reviewing any non-standard keyword arguments and moving them to the config dictionary as needed. By making these small adjustments, your Streamlit applications will be robust, warning-free, and prepared for future updates, maintaining their professional polish and functionality.

Why This Change? The Streamlit Philosophy

This shift in how st.plotly_chart handles parameters, particularly the deprecation of general **kwargs, isn't arbitrary. It's deeply rooted in the Streamlit philosophy of simplicity, clarity, and maintainability. Streamlit aims to be incredibly intuitive, allowing developers to build powerful data apps with minimal boilerplate code. However, relying too heavily on generic **kwargs can, paradoxically, reduce clarity over time. When parameters are passed implicitly, it becomes harder to trace their origin, understand their purpose, or anticipate how they might interact with future updates. By making parameters like width and height explicit, and by introducing a dedicated config dictionary for Plotly-specific options, Streamlit achieves several goals. First, it improves API clarity. Developers can immediately see which parameters are directly controlled by Streamlit and which are passed through to Plotly's own configuration. This reduces ambiguity and makes the function signature easier to understand. Second, it enhances future compatibility. With explicit parameters, Streamlit can evolve its API more gracefully. New features can be added, and existing ones modified, with less risk of accidentally breaking user code that relied on undocumented or implicitly handled **kwargs. Third, it promotes robust error handling. When arguments are well-defined, Streamlit can provide more specific and helpful error messages if a user passes an invalid option, rather than silently ignoring it or passing it to Plotly where it might cause unexpected behavior. This change is a testament to Streamlit's commitment to providing a stable and predictable environment for data app development, ensuring that while the platform grows, the developer experience remains as smooth and enjoyable as possible. It's a small price to pay for a more reliable and future-proof ecosystem.

Best Practices for Future-Proofing Your Streamlit Apps

To avoid encountering similar deprecation warnings in the future and keep your Streamlit applications running smoothly, adopting a few best practices is key. The goal is to write clean, explicit, and maintainable code that is resilient to updates in underlying libraries. Firstly, and perhaps most importantly, always check the official documentation. Streamlit's documentation is incredibly well-maintained and provides the most up-to-date information on functions, parameters, and any deprecation notices. Before integrating a new feature or troubleshooting an existing one, a quick glance at the docs can save you a lot of time and effort. This habit ensures you're always using the recommended approach. Secondly, keep your Streamlit and other library versions updated. The deprecation warning for st.plotly_chart kwargs, for example, is best addressed by ensuring you're on a recent Streamlit version where width and height are properly recognized as explicit parameters, not **kwargs. Regular updates not only bring new features but also include bug fixes and performance improvements, aligning your environment with the latest best practices. You can usually update with pip install --upgrade streamlit. Thirdly, favor explicit parameters over implicit ones or generic **kwargs. If a function offers a dedicated argument for a specific setting (like width for st.plotly_chart), use it. Reserve **kwargs or config dictionaries only when explicitly instructed or for truly dynamic, catch-all scenarios where no dedicated parameter exists. This makes your code's intent clearer and less prone to breaking changes. Fourth, modularize your code. Break down complex Streamlit apps into smaller, manageable functions or components. This makes it easier to isolate issues, test specific parts of your application, and update individual sections without affecting the entire codebase. When a deprecation warning appears, you'll know exactly which part of your code needs attention. Lastly, engage with the Streamlit community. The Streamlit forums and GitHub issues are excellent resources. If you encounter a warning or a problem that isn't clearly covered in the documentation, chances are someone else has faced it too. Learning from others' experiences and contributing your own insights can be incredibly beneficial for staying ahead of potential issues. By following these best practices, you'll not only resolve current warnings but also build a robust foundation for your Streamlit development journey, ensuring your data apps continue to impress and function flawlessly for years to come. These proactive steps reduce friction, streamline your development, and enhance the overall quality and longevity of your applications.

Conclusion

Dealing with a st.plotly_chart kwargs deprecation warning might seem like a minor annoyance at first, but it's actually a valuable signal from the Streamlit development team. It indicates a move towards a more explicit, stable, and future-proof API, making your data applications more robust in the long run. By understanding that certain parameters, like width="content", are transitioning from implicit **kwargs to dedicated arguments, and by learning to use the config dictionary for Plotly-specific settings, you're not just fixing a warning; you're upgrading your development practices. This shift is all about making your Streamlit experience smoother, clearer, and more efficient. Remember to keep your Streamlit installation updated, consult the official documentation regularly, and always opt for explicit parameter usage whenever possible. Embracing these changes ensures your interactive dashboards continue to shine, providing valuable insights without any unexpected hiccups. Your Streamlit applications deserve to be at their best, and by addressing these warnings, you're investing in their longevity and reliability. Keep building amazing things, and let Streamlit handle the heavy lifting while you focus on the data!

For more in-depth information, you can always refer to the Streamlit Documentation or explore the Plotly Python Graphing Library Documentation.