Resolving Streamlit's Plotly Chart Deprecation Warning

by Alex Johnson 55 views

What's Happening with st.plotly_chart and kwargs?

Are you a Streamlit enthusiast who loves creating interactive and beautiful data visualizations with Plotly? If so, you might have recently encountered a rather puzzling deprecation warning when using st.plotly_chart with parameters like width="content". This st.plotly_chart kwargs deprecation warning can be quite frustrating because, from your perspective, you're just using a perfectly documented and valid parameter, not some mysterious keyword argument (kwargs). It's like being told you're doing something wrong when you're simply following the instructions! This article is dedicated to unraveling this specific issue, explaining why it's happening, and giving you practical insights into how to handle it. We’ll dive into the technical details, offer solutions, and provide a clearer understanding of Streamlit’s evolution. When building Streamlit applications, we all want a smooth development experience, and unexpected warnings can certainly throw a wrench in the works. The warning message 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." However, this message seems to misapply when you're using width="content", a Streamlit-specific layout parameter, not a Plotly configuration. This nuance is precisely what causes confusion and necessitates a deeper look into the Streamlit codebase and its handling of parameters.

This particular plotly_chart kwargs deprecation warning isn't just a minor annoyance; it points to a deeper interaction problem within the Streamlit library itself. Developers expect st.plotly_chart to flawlessly integrate Plotly figures while respecting Streamlit's layout controls. The width="content" parameter is incredibly useful for creating responsive dashboards, allowing your charts to naturally fit the available space. Receiving a deprecation warning for such a fundamental and well-documented feature can lead to uncertainty about the stability of your code and whether you should change your approach. We’re going to explore the journey of these parameters, from the now-deprecated use_container_width to the current width argument, to illustrate how this particular warning has emerged. Our goal is to empower you with the knowledge to debug, understand, and, ultimately, move past this warning so you can continue building amazing data applications with Streamlit and Plotly without unnecessary friction.

Diving Deeper: The kwargs Deprecation Explained

The kwargs deprecation in st.plotly_chart is a crucial point for understanding Streamlit's evolving API. Historically, Streamlit offered the use_container_width boolean parameter to make your Plotly charts automatically scale to the width of their parent container. This was a very convenient feature for responsive design. However, as Streamlit matured, the design philosophy shifted towards a more unified and flexible layout system, leading to the deprecation of use_container_width and the introduction of a more generalized width parameter. The idea was to give developers more granular control, allowing values like width="content" (which behaves similarly to the old use_container_width but within a broader context), fixed pixel values, or percentages. This change was a positive step towards a more robust layout, aiming to simplify how users manage chart dimensions across different Streamlit elements. When use_container_width was deprecated, users were naturally advised to transition to the new width parameter, expecting a seamless experience. However, this is precisely where the current st.plotly_chart kwargs deprecation warning enters the picture, creating a scenario where following the new best practice still results in a warning.

The Transition from use_container_width to width

The transition away from use_container_width marked a significant improvement in how Streamlit handles responsive layouts for various components, including Plotly charts. The new width parameter provides a more flexible and consistent approach across different Streamlit elements, enabling developers to specify chart dimensions with greater precision. For instance, width="content" is designed to make the chart expand to the full width of its container, ensuring that your visualizations look great on any screen size. This shift was intended to streamline development and eliminate the need for separate, component-specific sizing parameters. Developers eagerly adopted the width argument, believing they were upgrading their code to align with Streamlit’s latest recommendations. The expectation was that using width="content" would be a straightforward, non-issue update. Unfortunately, the current st.plotly_chart kwargs deprecation warning arises precisely when using this officially recommended parameter, leading to understandable confusion. It's a classic case where an intended improvement inadvertently introduces a new, albeit temporary, challenge. The core of the problem lies not in the parameter itself, but in how Streamlit's internal validation mechanism is interpreting it in the context of kwargs, which we'll explore next. This subtle interaction is key to understanding why a seemingly valid parameter triggers a deprecation notice for variable keyword arguments.

Identifying the Root Cause: When Valid Parameters Become "Deprecated"

The heart of the st.plotly_chart kwargs deprecation warning lies in Streamlit's internal handling of parameters for the st.plotly_chart function. As highlighted in the issue description, the Streamlit codebase includes a specific check for kwargs:

if kwargs:
    show_deprecation_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 code snippet is designed to catch any unexpected keyword arguments passed to st.plotly_chart that aren't explicitly defined in its function signature. The problem, as many users have discovered, is that the width parameter (and potentially height as well) is being mistakenly captured by this kwargs check, even though width is a documented and valid parameter for st.plotly_chart. Instead of being processed as an explicit argument, it's being lumped into the catch-all kwargs bucket. This means that when you pass fig, width="content" to st.plotly_chart, the width="content" part is incorrectly seen as a "variable keyword argument" rather than a recognized, intended parameter. This is a classic case of a regression, where functionality that should work as intended based on documentation now triggers an unwarranted warning. It's not that width itself is deprecated, but rather Streamlit's internal logic is misinterpreting it as an arbitrary kwarg, which are indeed deprecated for Plotly configuration options (where config should be used instead). This fundamental misunderstanding within the code is the precise reason for the plotly_chart kwargs deprecation warning that's causing so much head-scratching among developers. Understanding this underlying mechanism is the first step towards effectively addressing and navigating this particular Streamlit challenge.

Reproducing the Warning: A Practical Example

To truly grasp the st.plotly_chart kwargs deprecation warning, let's walk through the reproducible code example that clearly demonstrates the issue. This example uses standard Plotly functionality combined with Streamlit, showcasing how a seemingly innocuous parameter triggers the warning. If you’ve encountered this problem, you’ll recognize this setup immediately. The core of the issue is not with the Plotly figure itself, but how Streamlit's st.plotly_chart function processes its own layout-related arguments, specifically the width parameter. The goal here is to display a simple Plotly bar chart within a Streamlit app and apply Streamlit's recommended width="content" setting.

Here’s the code that reliably triggers the plotly_chart kwargs deprecation warning:

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]))
fig.update_layout(width=500, height=360)

# Display the figure using st.plotly_chart with width="content"
st.plotly_chart(fig, width="content")

When you run this Streamlit application, you will notice that the st.plotly_chart kwargs deprecation warning appears prominently in your console or terminal. The warning message, as we discussed, incorrectly suggests that you are passing "variable keyword arguments" and should use the config argument for Plotly configuration. This is misleading because width="content" is a parameter specifically designed and documented by Streamlit to control the layout of the Streamlit component itself, not an internal Plotly configuration option. The fig.update_layout(width=500, height=360) line correctly configures the internal dimensions of the Plotly chart, while st.plotly_chart(fig, width="content") attempts to control how Streamlit renders that chart within the web application's layout. The warning arises because Streamlit's internal parsing of st.plotly_chart arguments incorrectly categorizes width="content" as a kwarg that should supposedly be handled by the config dictionary, instead of recognizing it as its own valid, explicit parameter. This example perfectly illustrates the regression nature of the bug, as this code pattern was previously clean and warning-free, highlighting the unexpected behavior that developers are currently facing when integrating Streamlit Plotly charts into their applications.

Your Options: Navigating the Deprecation Warning

Encountering the st.plotly_chart kwargs deprecation warning can be confusing, especially when you're diligently following Streamlit's official documentation. While this particular warning points to an internal logic issue within Streamlit (a regression, as established), it's important to understand your options for handling it. The main goal is to continue developing your Streamlit Plotly charts effectively without being sidetracked by misleading warnings. This section will guide you through understanding the recommended config argument in its proper context and offer some immediate, practical workarounds to keep your development workflow smooth.

Understanding the "Config Argument" Recommendation

The deprecation warning message, "Use the config argument instead to specify Plotly configuration options," is actually a valuable piece of advice, but it's misapplied to the width parameter in this specific scenario. Let's clarify its intended use. The config argument in st.plotly_chart is designed to pass Plotly.js configuration options directly to the underlying Plotly library. These options control aspects like whether the mode bar is visible, whether zooming is enabled, or custom button functionalities. For instance, if you wanted to hide the Plotly mode bar (the small toolbar that appears when you hover over a chart), you would use the config argument like this:

import plotly.graph_objects as go
import streamlit as st

fig = go.Figure(data=[go.Scatter(y=[2, 1, 4])])

# Using the config argument correctly for Plotly.js options
st.plotly_chart(fig, config={'displayModeBar': False})

This is the correct way to use the config argument. The width parameter, however, is a Streamlit-level layout control, not a Plotly.js configuration. It dictates how Streamlit renders the entire chart component within its own layout system. Therefore, attempting to pass width="content" or similar values through config would not work as intended for layout, and the current warning about kwargs mistakenly applies this advice to a Streamlit-specific parameter. Recognizing this distinction is crucial: config is for Plotly's internal behavior, while width is for Streamlit's external presentation. This clarity helps in understanding that the st.plotly_chart kwargs deprecation warning for width is a temporary misdirection rather than a call to fundamentally change how you handle chart dimensions.

Temporary Workarounds and Best Practices

Given that the st.plotly_chart kwargs deprecation warning for width="content" is a known regression, what are your immediate options? Firstly, it's important to understand that your code still works as intended; it's just generating a warning. The functionality of width="content" (or height) is not broken. Therefore, one approach is simply to tolerate the warning for now, knowing that it's an acknowledged issue that Streamlit developers are likely working to resolve. For most applications, a warning in the console does not impact the end-user experience. However, if you prefer a clean console, here are a few considerations:

  • Stay Updated with Streamlit: The best long-term solution is to keep your Streamlit library updated. Issues like this plotly_chart kwargs deprecation warning are often addressed in subsequent releases. Regularly check the Streamlit GitHub repository for updates or specific issue resolutions related to st.plotly_chart and kwargs. Community discussions and issue tracking are invaluable resources.
  • Focus on Essential Parameters: If the warning truly bothers you and you can live without width="content" for a particular chart, you might temporarily avoid using it or explicitly set a fixed width or height in fig.update_layout() that suits your needs. However, this often defeats the purpose of responsive design, so it might not be a viable workaround for all projects.
  • Review the st.plotly_chart Signature: Always refer to the official Streamlit documentation for st.plotly_chart to understand its expected parameters. This helps you differentiate between true kwargs that should be handled by config and legitimate Streamlit-specific parameters. As of now, width is a valid parameter, so the warning remains a regression.

For a more general warning suppression in Python (though not specifically for this type of Streamlit warning), you could use Python's warnings module. However, this is generally not recommended as it can mask other, more critical warnings. For Streamlit itself, there isn't a direct option to suppress specific deprecation warnings from its internal show_deprecation_warning function. The key takeaway is to prioritize building high-quality, functional applications. Understand that this particular plotly_chart kwargs deprecation warning is an acknowledged bug and is not a reflection of incorrect usage on your part when using width="content".

What's Next for Streamlit and Plotly?

The occurrence of the st.plotly_chart kwargs deprecation warning serves as a reminder that software development is a continuous process of evolution and refinement. Streamlit, as a rapidly growing framework, frequently updates its API to enhance performance, improve user experience, and introduce new features. Deprecations, while sometimes inconvenient, are a natural part of this cycle, indicating that older methods are being replaced by more efficient, consistent, or robust alternatives. In the case of Streamlit Plotly charts, the goal is always to provide the most seamless and powerful integration possible, allowing developers to create stunning visualizations with minimal effort.

This specific warning highlights the challenges of balancing API changes with backward compatibility, especially in a dynamic environment like Python where keyword argument handling can be complex. The st.plotly_chart kwargs deprecation warning is a temporary glitch in an otherwise robust effort to standardize layout controls. Future Streamlit versions will undoubtedly focus on resolving such internal inconsistencies, ensuring that documented parameters function without unexpected warnings. The continuous engagement from the Streamlit community, through bug reports and feature requests, plays a vital role in shaping these improvements. By reporting issues like this, users directly contribute to the framework's stability and future direction, helping the development team prioritize and address critical concerns. This collaborative approach ensures that Streamlit remains a cutting-edge tool for data application development.

Conclusion: Staying Ahead of Streamlit Updates

In conclusion, while the st.plotly_chart kwargs deprecation warning you encounter when using width="content" can be perplexing, it's important to remember that it signifies an internal regression within Streamlit, not a misstep in your code. You are correctly using a documented parameter. The warning itself, suggesting the use of a config argument for Plotly options, is relevant in other contexts but not for Streamlit's width parameter. This distinction is crucial for understanding the true nature of the issue.

As Streamlit continues to evolve, encountering such transient issues is part of the journey. The best approach is to stay informed, keep your library updated, and understand the core mechanics of how Streamlit interacts with external libraries like Plotly. Your contributions to the community, even through simple bug reports, help shape a better framework for everyone. Keep building those amazing Streamlit Plotly charts, confident that this minor hurdle will soon be resolved.

For further reading and to stay updated, consider visiting these trusted resources:

  • Streamlit Documentation: For the official and most up-to-date information on st.plotly_chart and other components, visit the Streamlit Docs.
  • Plotly Python Graphing Library: To deepen your understanding of Plotly figures and their configuration, refer to the Plotly Python Documentation.
  • Streamlit GitHub Issues: To track ongoing discussions and report new issues, check the Streamlit GitHub Issues page.