Fixing Streamlit Plotly Chart Kwargs Deprecation Warning

Are you diving into the exciting world of data visualization with Streamlit and Plotly, only to be met by a rather puzzling deprecation warning about kwargs when you try to set your chart's width="content"? You're not alone! Many developers have encountered this exact issue, feeling a bit stumped when using a seemingly straightforward, documented parameter. This article will walk you through understanding this specific plotly_chart kwargs deprecation warning, why it appears even with standard parameters, and how you can navigate it to ensure your Streamlit applications remain robust and warning-free. We'll explore the underlying causes, look at practical examples, and provide clear guidance to help you keep your interactive dashboards running smoothly without unexpected console clutter. Our goal is to demystify this technical hiccup, empowering you to build beautiful, responsive, and efficient Streamlit apps with Plotly without getting bogged down by cryptic messages. Let's make sense of this warning together and get your data visualizations shining!

This plotly_chart kwargs deprecation warning often surfaces during development, and while it might seem like a minor inconvenience, ignoring deprecation warnings can lead to bigger problems down the line as software evolves. Streamlit is constantly improving, and sometimes these improvements involve changes in how functions handle their arguments. In this particular case, the warning points towards a future where certain ways of passing arguments will no longer be supported. Specifically, when you use st.plotly_chart and provide the width="content" argument, the system flags it as if you're passing an arbitrary keyword argument that should instead be managed through a dedicated config object. This creates confusion because width is a documented and expected parameter for st.plotly_chart. It's not an arbitrary kwargs from a user's perspective, but the internal logic of Streamlit, specifically the show_deprecation_warning mechanism, is currently catching it. We'll delve into the code that triggers this, helping you understand the distinction between intended parameters and the kwargs that the warning is truly targeting. Ultimately, by grasping the nuances of this warning, you'll be better equipped to write cleaner, more future-proof Streamlit code, ensuring your applications continue to perform optimally and adapt gracefully to new updates.

Understanding the Plotly Chart Kwargs Deprecation

The plotly_chart kwargs deprecation warning in Streamlit is a crucial signal that indicates a shift in how arguments are expected to be passed to the st.plotly_chart function, particularly those related to Plotly's extensive configuration options. In Python, **kwargs (keyword arguments) allows a function to accept an arbitrary number of named arguments. While incredibly flexible, this can sometimes lead to less explicit APIs or make it harder for libraries to evolve without breaking user code. Streamlit's design philosophy encourages clarity and ease of use, and this deprecation is part of an effort to streamline how Plotly-specific configurations are handled. Instead of passing various Plotly configuration options directly as **kwargs to st.plotly_chart, the recommendation is to bundle them into a dedicated config dictionary argument. This approach provides a clearer separation of concerns: arguments that configure how Streamlit renders the chart (like width or use_container_width) versus arguments that configure the Plotly chart itself (like display mode bar, static plots, etc.). However, the current issue arises because a documented Streamlit-specific parameter like width="content" is inadvertently triggering this kwargs deprecation warning, creating a frustrating experience for developers who are simply following the official documentation. This is where the confusion truly lies: users are not explicitly passing **kwargs in the traditional sense, but the warning mechanism within Streamlit is still being activated, implying a misinterpretation or an overly broad check in its current implementation.

The deprecation, broadly speaking, aims to make the API for st.plotly_chart more predictable. Imagine Plotly has dozens of configuration options, from displayModeBar to scrollZoom to responsive. If Streamlit were to expose all of these directly as **kwargs, the st.plotly_chart function signature would become unwieldy, and maintaining compatibility as Plotly or Streamlit updates would be a nightmare. By channeling all Plotly-specific configurations through a single config dictionary, Streamlit can offer a more stable and cleaner interface. This config object is essentially a proxy for Plotly.js configuration attributes, allowing advanced customization without cluttering Streamlit's own function parameters. The problem we're observing, however, is that the width parameter, which is very much a Streamlit-level concern about how the component should scale within the app, is caught in this kwargs net. This suggests that internally, st.plotly_chart might be processing its own width parameter in a way that, at some point in the call stack, gets interpreted as a generic keyword argument before the deprecation check occurs. The warning message itself—"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"—reinforces this interpretation. It highlights that the system thinks you're passing Plotly config via kwargs when, in fact, you're using a Streamlit layout parameter. Understanding this distinction is key to navigating the warning, even if the immediate solution might involve waiting for a Streamlit patch to refine its warning logic.

Reproducing the Streamlit Plotly Warning

To truly grasp the plotly_chart kwargs deprecation warning that users are encountering, let's walk through the reproducible code example that clearly demonstrates this behavior. This snippet, deceptively simple, perfectly illustrates the problem. We're going to create a basic Plotly figure and then attempt to display it in a Streamlit app using the st.plotly_chart function, explicitly setting the width parameter. You’ll see firsthand how this triggers the warning, even when using what appears to be a perfectly valid and documented parameter. The core issue is that when st.plotly_chart receives width="content", it should interpret this as a parameter for its own layout management. However, due to the way its internal kwargs deprecation check is currently implemented, this seemingly innocuous parameter causes the kwargs warning to appear in your console or terminal where your Streamlit app is running. This behavior is both unexpected and confusing, as developers strive to write clean, warning-free code, especially when adhering to official documentation.

Let’s set up the environment first. You’ll need Streamlit and Plotly installed: pip install streamlit plotly. Once that's done, create a Python file, say app.py, and paste the following code:

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 Plotly figure in Streamlit with width="content"
st.plotly_chart(fig, width="content")

# A simple Streamlit element to show the app is running
st.write("Check your console for the deprecation warning!")

Now, run this Streamlit app from your terminal using streamlit run app.py. As soon as the application launches and the Plotly chart is rendered, take a look at the terminal where you executed the command. You will likely see a message similar to this:

2024-01-01 10:00:00.000 SomeLogger 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 kwargs deprecation warning is precisely the issue at hand. It pops up despite width being a recognized parameter for st.plotly_chart. The warning implies that width="content" is being treated as a variable keyword argument that should, in the future, be passed via the config dictionary. This is problematic because width is distinct from Plotly's own configuration; it’s about how Streamlit itself sizes the chart component. This example clearly demonstrates that the warning mechanism is currently over-eager, flagging legitimate Streamlit parameters as deprecated kwargs. This can lead to developers incorrectly believing they are misusing the st.plotly_chart function or that the width parameter itself is deprecated, when in fact, it's the internal warning logic that needs refinement. Understanding this reproduction is the first step toward finding clarity and potential solutions for managing these warnings effectively within your Streamlit applications.

Exploring the Expected vs. Current Behavior

When developers use st.plotly_chart and provide the width="content" parameter, their expected behavior is quite straightforward: the Streamlit component should adjust its width to fit the content within, without any warnings or fuss. This is a clear, documented feature of st.plotly_chart, designed to give users control over how their visualizations integrate into the responsive layout of a Streamlit application. The parameter width is specifically listed in Streamlit's API reference, indicating that it's an intentional and supported way to manage the display properties of the chart. Therefore, receiving a plotly_chart kwargs deprecation warning when using such a core, documented argument is both unexpected and counterintuitive. Users reasonably assume that if a parameter is explicitly part of the function's signature and documentation, its use should be valid and not trigger warnings intended for arbitrary, undocumented keyword arguments. This discrepancy between expectation and reality is at the heart of the confusion surrounding this particular issue.

However, the current behavior reveals a different story, as evidenced by the deprecation warning that appears in the console. The issue stems from an internal implementation detail within Streamlit's st.plotly_chart function, specifically within the logic that checks for deprecated kwargs. The problem description points to a snippet of code like this:

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 piece of code is designed to catch any leftover **kwargs that are passed to st.plotly_chart but are not explicitly handled by its fixed parameters. The intention is to warn users who might be passing Plotly.js configuration options directly as **kwargs instead of through the designated config dictionary. The width parameter, while an explicit argument in the st.plotly_chart signature, seems to be processed in a way that causes it to be caught by this if kwargs: check. This could happen if, for instance, width is first processed and then re-passed internally as a generic keyword argument to a deeper function call, or if the kwargs check is performed before all explicit parameters have been fully consumed and removed from the kwargs dictionary. Regardless of the exact internal mechanism, the result is that a legitimate parameter is incorrectly flagged. This makes the plotly_chart kwargs deprecation warning misleading in this specific context, as users are not misusing **kwargs but rather facing an issue with how Streamlit's own warning system is interpreting its parameters. This scenario highlights a regression, as this behavior was not present in previous versions where width="content" could be used without triggering such a warning. It points to a need for refinement in Streamlit's internal kwargs handling and deprecation warning logic to correctly distinguish between its own explicit parameters and the generic keyword arguments it intends to deprecate.

Solutions and Workarounds for the Deprecation Warning

Navigating the plotly_chart kwargs deprecation warning when using width="content" can be a bit tricky, especially since the warning appears for a seemingly legitimate and documented parameter. While the ideal solution involves Streamlit refining its internal logic to prevent this false positive, there are several approaches you can take right now to manage or mitigate the warning in your Streamlit applications. It's important to remember that width="content" itself is not deprecated; it's the warning mechanism that is currently over-eager. One common strategy is to be aware of the warning but understand its context. If your application works as expected and width="content" provides the desired layout, you might choose to tolerate the warning in your development console, knowing it’s a known issue rather than a critical error in your code. This isn't always ideal for clean console outputs, but it's a practical workaround until an official fix is released. Another approach involves explicitly setting the chart width using numerical values instead of `