Fixing `st.plotly_chart` Kwargs Deprecation Warning

by Alex Johnson 52 views

Welcome, fellow data enthusiasts and Streamlit developers! If you’ve been working with Streamlit to build beautiful, interactive data applications and integrating Plotly for your visualizations, you might have recently encountered a rather persistent and somewhat puzzling warning: "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 warning often pops up even when you believe you're not passing any variable keyword arguments, especially when simply trying to control your chart's size using width="content". It's a bit like getting a speeding ticket when you thought you were following all the rules! But don't worry, you're not alone in facing this peculiar issue. This deprecation message, while intended to guide developers towards a cleaner API, has created a bit of confusion, particularly with the width="content" parameter that replaced use_container_width. Many users, including yourself, have reported seeing this warning in Streamlit version 1.50.0 even when adhering to the updated documentation for responsive chart sizing. It implies that a standard, documented parameter is being mistakenly identified as an arbitrary keyword argument. This situation can be quite frustrating, as it clutters your console and raises concerns about future compatibility, even if your application functions correctly in the short term. In this comprehensive guide, we're here to unravel this mystery, understand why this specific warning appears, and, most importantly, show you how to fix it so your Streamlit apps can run smoothly and silently once more. We'll dive deep into what kwargs actually are, how Streamlit handles Plotly charts, and explore the best practices to keep your visualizations vibrant and your console clean. By the end of this article, you'll have a clear roadmap to navigate this deprecation, ensuring your Streamlit-Plotly synergy remains as powerful and efficient as ever, allowing you to focus on delivering insightful data experiences without worrying about cryptic warnings.

Unpacking the st.plotly_chart Deprecation Warning

Let's start by dissecting the warning message itself. The full message, "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," points to a significant shift in how Streamlit intends for users to pass additional settings to their Plotly charts. Historically, st.plotly_chart might have allowed developers to pass arbitrary keyword arguments (often referred to as **kwargs in Python) directly to the underlying Plotly rendering mechanism. While convenient, this approach can sometimes lead to ambiguity or make it harder for the Streamlit team to maintain a stable API, as it effectively exposes internal Plotly options through Streamlit's interface without strict control. To foster a cleaner, more predictable API, Streamlit is moving towards a more explicit way of handling Plotly-specific configurations via a dedicated config parameter. This means that instead of relying on implicit passthrough of kwargs, you're now encouraged to bundle all Plotly-specific settings into a dictionary and pass it as the config argument. This change aims to differentiate Streamlit's own parameters (like width, height, use_container_width) from true Plotly configuration options, making the API more robust and easier to understand for developers. However, the puzzle arises when this warning appears even when users are seemingly only utilizing documented Streamlit parameters, such as width="content", which logically should be handled directly by Streamlit and not fall under the umbrella of "variable keyword arguments" meant for Plotly's config. This situation points to a potential over-eagerness in the deprecation checker, catching even valid Streamlit parameters within its kwargs net. The issue specifically highlighted in the problem description notes that with Streamlit version 1.50.0, using width="content" triggers this deprecation warning. This is particularly frustrating because width="content" replaced the previously deprecated use_container_width, and users are attempting to follow the new recommended API. The expectation is that width="content" should not be treated as a variable keyword argument destined for Plotly's config, but rather as a core Streamlit layout parameter for the chart component itself. This discrepancy suggests a temporary regression or an unforeseen side effect in how the deprecation logic was implemented in specific Streamlit versions, leading to valid parameters being misidentified. Understanding this distinction is crucial: config is for Plotly-specific details (like toggling toolbars or setting static image options), while width and height are about how the Streamlit component itself fits into your app's layout. The deprecation aims to streamline this, not complicate it by misclassifying Streamlit's own arguments. This change, while ultimately beneficial for API clarity, certainly caused a hiccup for users upgrading to 1.50.0 or similar versions. It underscores the importance of not just observing warnings, but also understanding their root cause in the context of library updates and intended usage patterns.

Understanding kwargs in Python and Streamlit

To truly grasp why this warning appears, it's helpful to take a quick detour into the world of Python's kwargs (keyword arguments) and how they interact with library design. In Python, **kwargs is a special syntax that allows a function to accept an arbitrary number of keyword arguments. When you define a function like def my_function(param1, **kwargs):, any named arguments passed to my_function that aren't param1 will be collected into a dictionary called kwargs. This is incredibly flexible for building APIs that need to accept a wide range of optional parameters, or when a function acts as a wrapper, passing these arguments down to another underlying function. For instance, st.plotly_chart acts as a wrapper around Plotly's rendering capabilities. Historically, Streamlit likely leveraged **kwargs to allow users to pass various Plotly-specific configuration options directly, such as displayModeBar=False or scrollZoom=True, without Streamlit needing to explicitly define each of these as its own parameter. While this offered great flexibility, it also blurred the lines between Streamlit's own parameters and those intended for Plotly. When st.plotly_chart(fig, width="content", displayModeBar=False) was called, width="content" was a Streamlit parameter, but displayModeBar=False would likely be collected into kwargs and passed to Plotly. The current deprecation aims to make this distinction explicit: Streamlit now wants all Plotly-specific options to be neatly packaged into a dictionary and passed via the dedicated config parameter. So, instead of st.plotly_chart(fig, displayModeBar=False), the intended way is st.plotly_chart(fig, config={'displayModeBar': False}). This approach enhances clarity, makes the Streamlit API more predictable, and allows the Streamlit team to evolve their component without being tightly coupled to every single Plotly configuration option. It also helps in validation and error checking, as config can be designed to specifically accept Plotly options. The problem arises when a parameter like width="content", which is clearly a Streamlit-specific parameter, gets incorrectly flagged as a generic kwargs meant for the config dictionary. This indicates a temporary misclassification within Streamlit's internal logic, specifically in version 1.50.0. The internal if kwargs: check, designed to catch miscellaneous Plotly options, seems to be broadly interpreting width="content" as falling into this category. This is a crucial point because it's not the user's fault for passing width="content"; they are following the documented Streamlit API. It's an internal implementation detail causing this warning for a parameter that should be handled natively by Streamlit. Therefore, while config is the correct path for Plotly-specific configurations, parameters like width and height should ideally be treated as first-class Streamlit arguments, not as part of the kwargs catch-all. Understanding this separation of concerns – Streamlit parameters versus Plotly configurations via config – is key to writing robust and future-proof Streamlit applications, and helps you differentiate between a genuine API change you need to adapt to and a potential bug in the deprecation warning system itself.

Practical Solutions: Eliminating the Deprecation Warning

When you're faced with the st.plotly_chart kwargs deprecation warning because you're using width="content", it can feel a bit like you're caught between a rock and a hard place. You want your charts to be responsive and fit their container, and width="content" is the modern, recommended way to achieve this in Streamlit, replacing use_container_width. Yet, it's triggering a warning about kwargs that should be for Plotly-specific configurations. So, what's a developer to do? The most immediate and often effective solution is to understand that, in versions like 1.50.0, this particular warning associated with width="content" is likely a temporary bug or an overzealous implementation of the deprecation check within Streamlit itself, rather than you misusing width. Streamlit's intent is for width to be a native Streamlit parameter. Therefore, the first step should always be to ensure you are on the latest stable version of Streamlit. Developers frequently release patches to fix such regressions, and an update might resolve the issue without any code changes on your part. You can easily update your Streamlit installation using pip: pip install --upgrade streamlit. Once updated, re-run your application to see if the warning persists. If it does, and you absolutely need to suppress the warning while waiting for a patch, one temporary workaround (though not ideal as it hides potential future warnings) could involve filtering Python warnings, but it's generally better to address the root cause. A more robust approach, if width="content" continues to be problematic, involves considering alternatives for controlling chart layout. While width="content" is designed for dynamic sizing, you can still control the initial width and height of your Plotly figure directly within Plotly itself using fig.update_layout(width=..., height=...). This provides fixed dimensions. If you want a chart to occupy the full width of a Streamlit column, you can often achieve this without width="content" on st.plotly_chart by letting Plotly render its default size and then using Streamlit's layout features like st.columns to manage the space around it. However, the ideal scenario is for width="content" to function as intended without warnings. For actual Plotly configuration options (the ones the deprecation is truly for), you should indeed migrate them to the config argument. For example, if you used to do st.plotly_chart(fig, displayModeBar=False, scrollZoom=True), you would now write: st.plotly_chart(fig, config={'displayModeBar': False, 'scrollZoom': True}). This is the correct way to handle Plotly-specific settings as per the new API. Let's revisit the provided reproducible code example to clarify:

import plotly.graph_objects as go
import streamlit as st

fig = go.Figure()
fig.add_trace(go.Barpolar(r=[1], theta=[0], width=[120]))
fig.update_layout(width=500, height=360)

st.plotly_chart(fig, width="content") # This line triggers the warning

In this example, the width="content" is the specific trigger. If a Streamlit update doesn't fix it, you might consider if fig.update_layout's width and height settings are sufficient for your needs, or if you can structure your Streamlit app using st.columns to implicitly manage the chart's display area without needing width="content" on the st.plotly_chart call itself. For instance, placing the chart inside a st.column that stretches to the desired width can often yield similar visual results. Ultimately, for the specific width="content" issue, the best solution is a fix from the Streamlit team, as it appears to be a misclassification of a legitimate Streamlit parameter. Until then, ensure your Streamlit is updated, and if the warning persists and impacts your workflow, consider reporting it with your version details or seeking alternative layout strategies.

Best Practices for Using Streamlit and Plotly Together

Integrating Streamlit and Plotly effectively means not just getting rid of deprecation warnings, but also adopting habits that lead to robust, maintainable, and visually appealing applications. One of the most fundamental best practices is to stay updated with both libraries. Software evolves rapidly, and deprecation warnings are often the first sign that an API is changing. Regular pip install --upgrade streamlit and pip install --upgrade plotly commands ensure you're benefiting from the latest features, performance improvements, and, crucially, bug fixes that might resolve issues like the width="content" deprecation warning automatically. Ignoring updates can lead to accumulating technical debt and unexpected breakages down the line. Closely tied to staying updated is the habit of referencing the official documentation. Both Streamlit and Plotly maintain excellent, comprehensive documentation that is your primary source of truth for API usage. When a warning appears, a quick check of the latest st.plotly_chart documentation can clarify if a parameter has changed its name, moved, or if there's a new recommended way of achieving a certain effect, like the transition from use_container_width to width="content", and the new config parameter for Plotly options. Relying on outdated tutorials or assumptions can quickly lead you astray. Another powerful technique for building flexible layouts in Streamlit is leveraging st.columns and st.expander. While st.plotly_chart offers some direct control over width, wrapping your charts in Streamlit's layout primitives provides a much more granular and responsive control over your application's appearance. For example, instead of struggling with width="content" if it's causing issues, you can place your st.plotly_chart call within a st.column to implicitly manage its width within the grid system. This often provides a more predictable layout experience and can indirectly achieve the "container width" effect without relying on the problematic parameter. st.expander can also be useful for tucking away less critical charts or interactive elements, keeping your main dashboard clean. Furthermore, it's a great practice to isolate chart logic from Streamlit display logic. This means creating your Plotly go.Figure() objects and configuring their traces and layouts independently of how they will be displayed in Streamlit. This separation makes your code easier to read, debug, and reuse. Your Plotly figure creation functions should ideally return a fully configured go.Figure object, which is then simply passed to st.plotly_chart. This prevents your Streamlit display code from becoming cluttered with complex Plotly configuration details. For instance, rather than embedding all layout updates directly before st.plotly_chart, consider a function that generates the figure: def create_my_chart(data): fig = go.Figure(...); fig.update_layout(...); return fig. Then, in Streamlit: st.plotly_chart(create_my_chart(my_data), config=my_plotly_config). Finally, when using the config argument for Plotly-specific settings, be mindful of the options you pass. Plotly has a vast array of configuration options, and the config dictionary is designed to accept them. Explore Plotly's own documentation for config options, such as displayModeBar, scrollZoom, editable, staticPlot, and responsive, to fine-tune the user interaction with your charts. This explicit approach ensures that Streamlit can clearly distinguish its own layout parameters from the specialized instructions you're giving to the Plotly renderer, leading to fewer unexpected warnings and a more maintainable codebase. Adhering to these best practices will not only help you resolve current deprecation warnings but also prepare your applications for future updates and changes in both Streamlit and Plotly, fostering a smooth and efficient development workflow.

What to Do If You Encounter This Warning

Encountering a deprecation warning, especially one that seems to misclassify a legitimate parameter, can be a moment of confusion and frustration. However, knowing the right steps to take can quickly turn that frustration into a productive debugging session. The absolute first thing you should always do is check for Streamlit updates. As we've discussed, issues like the width="content" deprecation warning in 1.50.0 often stem from temporary regressions or minor implementation hiccups that are quickly identified and patched by the development team. Running pip install --upgrade streamlit in your terminal is a simple yet powerful step. After upgrading, restart your Streamlit application to see if the warning persists. It's often the quickest and easiest fix, as the Streamlit team is very responsive to community-reported bugs and frequently releases patches to address them. If, after updating, the warning still appears, and you're confident that width="content" (or any other documented Streamlit parameter) is being incorrectly flagged, the next crucial step is to report the issue. The Streamlit community and development team thrive on user feedback, and a clear, concise bug report is invaluable for maintaining the quality and stability of the library. When reporting, always include the following critical pieces of information:

  1. Your Streamlit version: You can find this by running st.__version__ in your script or streamlit --version in your terminal.
  2. Your Python version.
  3. Your Operating System and Browser (e.g., MacOs 26.1, Chrome).
  4. A minimal reproducible code example (like the one provided in the original issue). This snippet should be as short as possible, clearly demonstrating the problem without extraneous code, making it easy for developers to replicate the issue quickly.
  5. Expected behavior vs. current behavior: Clearly state what you expect to happen (e.g., no warning when using width="content") and what is actually happening (the specific deprecation warning message you receive).

This detailed information allows the developers to quickly pinpoint the problem and work on a fix, benefiting the entire community. While waiting for a patch, you might need to implement workarounds. For the specific width="content" issue, if you need immediate relief from the warning, you could temporarily avoid passing width="content" to st.plotly_chart. Instead, you could rely on setting the width and height directly within your Plotly figure's layout using fig.update_layout(width=None, height=None) or specific pixel values, depending on your needs. For responsive behavior, you can often achieve a similar effect by placing your st.plotly_chart within a st.container() or a st.column() without explicitly specifying width="content" on the chart itself. Streamlit's layout system is quite flexible, and sometimes allowing the chart to render at its default Plotly size within a Streamlit layout element can work just as well, especially if your goal is simply for it to fill the available space. Another workaround, although generally discouraged for production code unless absolutely necessary, is to suppress specific warnings. Python's warnings module allows for filtering: import warnings; warnings.filterwarnings("ignore", category=DeprecationWarning, module='streamlit'). However, this should be used with extreme caution, as it can hide other important warnings that you should be addressing. The most recommended approach remains to stay updated, report issues clearly, and use the config argument correctly for actual Plotly configurations. By following these steps, you not only solve your immediate problem but also contribute to the improvement of the Streamlit library for the entire community. Your proactive engagement helps ensure that Streamlit remains a robust and enjoyable platform for data app development.

Conclusion

Navigating deprecation warnings is a common part of software development, especially when working with rapidly evolving libraries like Streamlit and Plotly. The st.plotly_chart kwargs deprecation warning when using width="content" is a prime example of how API changes, even well-intentioned ones, can sometimes lead to unexpected behavior. We've explored that while config is the correct, explicit way to pass Plotly-specific options, the issue with width="content" likely points to a temporary regression in Streamlit's deprecation handling (specifically around version 1.50.0). The key takeaways are to always keep your libraries updated, thoroughly read and understand official documentation, and separate Streamlit layout parameters from Plotly configurations using the config argument. When faced with persistent or puzzling warnings, providing clear, reproducible bug reports to the Streamlit team is crucial for driving improvements. By embracing these best practices, you can ensure your Streamlit applications remain stable, performant, and free from distracting console warnings, allowing you to focus on building amazing data experiences.

For more in-depth information and to stay abreast of the latest developments, we highly recommend consulting these trusted resources:

  • Streamlit Documentation: For all things Streamlit, including API references and guides: https://docs.streamlit.io
  • Plotly Python Graphing Library: For comprehensive documentation on creating Plotly figures and their configuration options: https://plotly.com/python
  • Streamlit Community Forum: A great place to ask questions, share insights, and find solutions with other Streamlit users: https://discuss.streamlit.io