Streamlit Plotly: Solving The Kwargs Deprecation Warning

by Alex Johnson 57 views

Welcome, fellow data enthusiasts and Streamlit developers! Have you recently encountered a rather confusing kwargs deprecation warning when using st.plotly_chart in your Streamlit applications? Specifically, a message like "Variable keyword arguments for st.plotly_chart have been deprecated... Use the config argument instead" popping up, even when you're just trying to set a simple width="content"? If so, you're in the right place! This article will demystify this warning, explain why it's happening, and guide you through the best practices to resolve it, ensuring your Streamlit Plotly charts shine brightly without any annoying console clutter.

Unpacking the Streamlit Plotly kwargs Deprecation Warning

Let's dive right into the heart of the matter: the Streamlit Plotly kwargs deprecation warning. This particular message, which many developers are seeing when they use st.plotly_chart with seemingly innocent parameters like width="content", can be quite perplexing. It basically tells you that using variable keyword arguments (or **kwargs) directly with st.plotly_chart is on its way out and that you should consider using the config argument for Plotly-specific configurations instead. But here's the kicker: many of us aren't explicitly passing any **kwargs! We're just using a documented parameter like width or height.

This deprecation warning isn't just a minor annoyance; it can be a source of confusion and even frustration. When you're trying to build a clean, robust Streamlit application, seeing unexpected warnings can make you question your code, even when you're following the documentation. The problem arises because Streamlit's internal handling of arguments for st.plotly_chart has evolved. What was once accepted implicitly, or passed through a generic **kwargs catch-all, is now being scrutinized more closely. The width parameter, in particular, seems to be a common trigger for this alert, even though it's a standard and crucial way to control your chart's layout within Streamlit. This indicates a potential mismatch between how Streamlit's warning system interprets arguments and how developers naturally use the component.

The good news is that this is primarily a warning, not an error that will crash your app. Your charts will still render (for now!), but it's a clear signal that the underlying API is changing. Ignoring deprecation warnings can lead to broken code in future updates, so it's always best practice to understand and address them proactively. Streamlit is constantly being refined to offer a more stable and predictable API, and these warnings are part of that evolutionary process. While the intent is to improve clarity and prevent misuse of **kwargs for Plotly configurations, in some cases, it might inadvertently flag perfectly valid st.plotly_chart parameters, leading to this current state of developer bewilderment. We'll explore the deeper technical reasons in the next section, so you can fully grasp why your width="content" is causing a stir.

Diving Deeper: Why This Warning Appears for width="content"

Understanding the root cause of the plotly_chart kwargs deprecation warning for parameters like width="content" requires a peek under Streamlit's hood. Historically, Streamlit components, including st.plotly_chart, might have accepted a broader range of keyword arguments. Some of these were direct parameters for the Streamlit function itself, while others might have been intended as passthrough arguments for the underlying Plotly library or simply caught by a generic **kwargs mechanism. Over time, as APIs mature, libraries often tighten their argument parsing to ensure clarity, prevent unexpected behavior, and provide more explicit control.

The reproducible code example provided, st.plotly_chart(fig, width="content"), perfectly illustrates the issue. Here, width is a documented parameter for st.plotly_chart, specifically designed to control how the Plotly figure resizes within your Streamlit app. It's not an arbitrary keyword argument. Yet, the warning appears. This suggests that Streamlit's internal logic, particularly the if kwargs: show_deprecation_warning(...) block introduced in recent updates (as highlighted in the issue description), is perhaps too aggressive or misinterpreting certain valid parameters as undocumented kwargs.

To elaborate, the warning message itself explicitly 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 primarily intended for cases where users might be passing Plotly-specific configuration options (like displayModeBar, scrollZoom, etc.) directly as keyword arguments to st.plotly_chart, rather than wrapping them within the dedicated config dictionary. For example, if you used to do st.plotly_chart(fig, displayModeBar=False), that would correctly trigger the deprecation warning, and the fix would be st.plotly_chart(fig, config={'displayModeBar': False}).

However, when width="content" triggers this same warning, it points to an unintended side effect. width is a Streamlit-level parameter for st.plotly_chart, not a Plotly configuration option. It sets the layout behavior within the Streamlit app, similar to how use_container_width used to work (which has itself been deprecated and replaced by the more flexible width parameter with values like "container" or "content"). The most likely scenario is that in the refactoring efforts to make argument parsing more explicit, the width parameter is being inadvertently captured by the **kwargs check, or its internal handling has changed in a way that makes it appear as a kwargs entry to the warning system. This is often an oversight in development and is usually addressed in subsequent patches. So, while the warning is designed to push users towards the config argument for Plotly-specific settings, it's mistakenly catching Streamlit's own styling parameters in certain situations, leading to this current developer dilemma. Recognizing this distinction is key to finding the right solution, which we'll explore next.

Your Guide to Resolving the Plotly Chart kwargs Warning

When faced with the solving plotly_chart kwargs deprecation warning, especially for parameters like width="content", it's important to differentiate between two main scenarios. First, the intended use of the config argument for Plotly-specific options. Second, the peculiar case where a valid st.plotly_chart parameter like width is mistakenly triggering the kwargs warning.

Scenario 1: Correctly Using the config Argument for Plotly Options

If you were previously passing Plotly configuration options directly as keyword arguments to st.plotly_chart, the fix is straightforward: move them into the config dictionary. This is the official, recommended way and will prevent the intended deprecation warnings.

  • Old (deprecated) way:

    import plotly.graph_objects as go
import streamlit as st

fig = go.Figure(data=[go.Bar(y=[2, 3, 1])])
st.plotly_chart(fig, displayModeBar=False, scrollZoom=True) # These are Plotly config options

  • New (correct) way:

    import plotly.graph_objects as go
import streamlit as st

fig = go.Figure(data=[go.Bar(y=[2, 3, 1])])
st.plotly_chart(fig, config={'displayModeBar': False, 'scrollZoom': True})

This approach ensures that Streamlit can clearly distinguish its own parameters from those meant for Plotly's rendering engine, leading to cleaner code and fewer warnings.

Scenario 2: Handling width="content" Triggering the kwargs Warning (The Current Bug)

This is the specific issue many users are encountering, where st.plotly_chart(fig, width="content") or st.plotly_chart(fig, width="container") unexpectedly throws the kwargs deprecation warning. As established, width is a legitimate parameter for st.plotly_chart, not a variable keyword argument, and not a Plotly configuration option that should go into config. Therefore, its inclusion in the kwargs warning is an unintended bug within Streamlit's implementation.

Unfortunately, as of Streamlit version 1.50.0 (and potentially slightly before/after), there isn't an alternative, documented parameter to width="content" that achieves the same layout behavior without triggering the warning, if this warning is bugged. Here’s what you can do:

  1. Acknowledge it's likely a bug: Understand that you're using width correctly according to the documentation. The warning is most likely a false positive caused by an internal implementation detail that Streamlit developers will likely fix in a future release.

  2. Monitor Streamlit Releases: Keep an eye on Streamlit's official release notes. Bugs like this are often identified and patched quickly. Updating your Streamlit library regularly (pip install --upgrade streamlit) is the best way to receive these fixes.

  3. Report the Issue (if not already done): The user's input clearly shows this has been reported as a regression. If you encounter similar issues or believe your specific case is unique, contributing to the Streamlit GitHub issues page helps the development team prioritize and address these problems promptly.

  4. Temporary Workaround (Use with Caution): If the warning message is severely disrupting your development flow or CI/CD pipelines, you can temporarily suppress warnings. However, this is strongly discouraged as it can hide other, more critical warnings. A better approach might be to filter specific warnings if your Python environment allows it, but this adds complexity and should be removed once the bug is fixed.

    # Example: Not recommended for general use, but for extreme temporary scenarios
import warnings
warnings.filterwarnings("ignore", category=DeprecationWarning, module="streamlit.elements.plotly_chart")
# Then your code:
# st.plotly_chart(fig, width="content")

  5. Revisit Figure Sizing (If width="content" isn't critical): If width="content" isn't strictly necessary and use_container_width=True isn't an option (as it's deprecated), consider setting the width directly in the Plotly figure layout or using width="container" if it doesn't trigger the warning for you. Remember that width="container" makes the chart expand to the full width of the Streamlit column, while width="content" attempts to size it based on its intrinsic content.

The most important takeaway is to distinguish between correct usage of the config argument for Plotly settings and this specific bug where width is being flagged. For the latter, patience and keeping your Streamlit version updated are your best allies.

Best Practices for Robust Streamlit Plotly Integrations

Beyond addressing specific warnings, adopting Streamlit Plotly best practices ensures your applications are both functional and future-proof. Building robust integrations means writing code that is clean, efficient, and resilient to library updates.

First and foremost, always refer to the latest Streamlit documentation. The Streamlit team is constantly improving the library, and the documentation is your most reliable source for current best practices, new features, and changes to existing APIs. While this article helps address a specific issue, the official docs will always provide the most up-to-date guidance on parameters for st.plotly_chart, including how to correctly use width, height, and the config argument. Regularly checking for updates prevents unexpected behavior and keeps you aligned with the latest recommended patterns.

Secondly, keep your Streamlit and Plotly libraries updated. As we've seen with the kwargs deprecation warning, library updates often introduce breaking changes or deprecations, but they also bring performance improvements, bug fixes, and new features. A simple pip install --upgrade streamlit plotly command can save you headaches by ensuring you're running the most stable and feature-rich versions. Many bugs, like the one discussed, are often resolved quickly in patch releases, so staying current is crucial.

Structured code is key for maintainability. When working with Plotly charts in Streamlit, it's a good practice to separate the creation of your Plotly go.Figure object from its display in Streamlit. This modular approach makes your code easier to read, debug, and reuse. Define your figure, add traces, and configure layouts in one block, and then pass the complete figure object to st.plotly_chart. Avoid mixing complex Plotly logic directly within your Streamlit display calls. This separation also makes it easier to apply universal Plotly configurations or Streamlit-specific sizing without cluttering your logic.

Consider error handling and logging in your Streamlit applications. While Streamlit handles many errors gracefully, explicitly catching exceptions, especially when dealing with data processing or complex chart generation, can provide a better user experience. Using Python's logging module or st.exception can help you diagnose issues effectively, particularly when deploying applications. Although the kwargs warning is not an error, it's a good reminder to be vigilant about all messages from your environment.

Finally, engage with the community. Streamlit has a vibrant and supportive community through its forums and GitHub repository. If you encounter an issue that isn't clearly documented or discussed, chances are someone else has faced it or can offer insight. Contributing bug reports, feature requests, or simply participating in discussions helps everyone. This collaborative spirit is what makes open-source tools like Streamlit so powerful and constantly evolving. By following these best practices, you'll not only resolve current warnings but also build more resilient and effective Streamlit applications for the long run.

Conclusion: Navigating Streamlit's Evolving Landscape

Navigating the dynamic landscape of modern web frameworks and data visualization libraries like Streamlit and Plotly can sometimes feel like a puzzle, especially when unexpected warnings appear. The plotly_chart kwargs deprecation warning for parameters such as width="content" is a perfect example of how library evolution can introduce temporary quirks. We've explored that while the config argument is the correct destination for Plotly-specific options, the width parameter's current behavior of triggering this warning is likely an oversight that Streamlit's developers are addressing.

The journey to a robust Streamlit application is one of continuous learning and adaptation. By understanding the underlying reasons for such warnings, staying informed through documentation and community channels, and applying best coding practices, you empower yourself to build powerful, interactive data apps with confidence. Remember, deprecation warnings are not roadblocks but rather signposts guiding us toward more stable and efficient ways of working with our favorite tools.

Keep your Streamlit and Plotly libraries updated, consult the official documentation regularly, and don't hesitate to engage with the vibrant Streamlit community. Your proactive approach ensures your applications remain performant, visually appealing, and free from unexpected hiccups.

For further reading and the latest updates, please refer to these trusted resources:

  • Streamlit Documentation: For all things Streamlit, including detailed API references and guides on components like st.plotly_chart, visit the official Streamlit documentation.
  • Plotly Documentation: To deepen your understanding of Plotly figures, traces, and layouts, the Plotly documentation is an invaluable resource.
  • Streamlit GitHub Issues: If you encounter a new bug or want to track the progress of existing ones, the Streamlit GitHub issues page is the place to go.