Streamlit `st.plotly_chart` `kwargs` Deprecation Warning

by Alex Johnson 57 views

Introduction to the Problem: Navigating the st.plotly_chart Deprecation Warning

Hey there, fellow Streamlit enthusiasts and data visualization wizards! If you've been working with Streamlit lately, especially when trying to make your Plotly charts look just right with options like width="content", you might have stumbled upon a rather persistent and somewhat puzzling deprecation warning related to kwargs. It's a common scenario: you’re trying to use what seems like a perfectly documented parameter, like width="content" or height="content", with st.plotly_chart, and then BAM!—a message pops up, telling you that variable keyword arguments (kwargs) are deprecated and will be removed. This can be quite confusing, right? Especially when you're confident you haven't passed any explicitly variable keyword arguments yourself. This isn't just a minor annoyance; it’s a warning that could signal future breaking changes if not addressed. Understanding why this kwargs deprecation warning appears, even when you're using seemingly standard parameters, is key to keeping your Streamlit applications robust and future-proof. We're going to dive deep into this specific issue, understand its roots, and explore how to handle it effectively, ensuring your interactive dashboards continue to shine without unexpected hiccups. We'll walk through the exact problem, illustrate it with a simple code example, and discuss what's happening under the hood in Streamlit's st.plotly_chart function that triggers this message. So, let’s clear up this confusion and get your Plotly charts back on track, free from those pesky deprecation warnings. This article will be your comprehensive guide to understanding and resolving the st.plotly_chart kwargs deprecation warning, particularly when you're just trying to specify chart dimensions like width="content". We want your Streamlit apps to be smooth, performant, and error-free, so let's get to the bottom of this together. We'll explore the context of this warning, the code changes that might have led to it, and practical strategies to ensure your applications remain stable and up-to-date with Streamlit's evolving API. This isn't just about silencing a warning; it's about deeply understanding the tools we use to build amazing data applications. By the end, you'll have a clear picture of how to manage st.plotly_chart parameters effectively, avoiding unexpected kwargs deprecation messages.

Deep Dive into the st.plotly_chart Deprecation: Unpacking the kwargs Mystery

This section will peel back the layers of the st.plotly_chart deprecation warning, specifically focusing on why kwargs are flagged even with seemingly innocent parameters like width="content". It’s crucial for every Streamlit developer to grasp the nuances of this change, as it impacts how we integrate Plotly visualizations into our applications. The warning message itself indicates that "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 statement immediately makes us wonder: if width isn't a variable keyword argument in the traditional sense, why is it caught in this net? Let's break this down further.

What's the kwargs Deprecation About?

The kwargs deprecation is part of a larger effort within the Streamlit ecosystem to refine its API, making it more predictable, maintainable, and robust for developers. When a function uses **kwargs in its signature, it essentially acts as a catch-all for any additional keyword arguments that aren't explicitly defined. While incredibly flexible, this can become a double-edged sword. For st.plotly_chart, many Plotly-specific configuration settings could be passed directly as kwargs. However, as Streamlit evolves, and new parameters are added to st.plotly_chart itself (like width, height, use_container_width), there's a risk of name collisions. If a Plotly configuration option shares the same name as a new Streamlit parameter, which one should take precedence? Or how should they interact? To avoid such ambiguities and ensure a clearer separation of responsibilities, Streamlit is now enforcing that Plotly-specific configuration options be passed via a dedicated config dictionary. This makes the intention explicit: anything in config is for Plotly's rendering engine, while other direct parameters like width are for how Streamlit displays the chart within its own layout. This change, though initially causing some head-scratching, ultimately leads to a more stable and understandable API, reducing the likelihood of unexpected behavior or breaking changes in future versions. It's about bringing order to what was a very flexible, but potentially chaotic, parameter handling system. This shift empowers developers with a clearer mental model of how st.plotly_chart consumes its arguments, distinguishing between parameters that control Streamlit's rendering of the chart container and those that configure the Plotly chart itself.

The width="content" Conundrum: Why It Triggers kwargs

Here’s where the plot thickens and the immediate confusion arises. You're simply trying to use width="content" or height="content" with st.plotly_chart—parameters that are clearly documented in the Streamlit API as standard ways to control your chart's dimensions. Yet, you get the kwargs deprecation warning. Why? The root cause lies in how Streamlit internally processes these arguments. In earlier versions, parameters like width and height might have been implicitly handled, or their presence didn't trigger the kwargs check in the same way. However, with the recent API refinements and the explicit introduction of a kwargs deprecation check, Streamlit’s code now detects any non-explicitly defined argument as part of kwargs that might have been intended for Plotly's internal configuration. Even though width and height are documented parameters for st.plotly_chart, if the implementation of the deprecation check is too broad, it can mistakenly categorize these legitimate arguments as part of the generic **kwargs catch-all intended for Plotly's config. This is precisely what happened. The code snippet introduced to catch deprecated kwargs for Plotly config options essentially performs a check: if kwargs: show_deprecation_warning(...). The problem is that width="content" (or other similar parameters not explicitly removed from the kwargs collection before this check) ends up still being present in kwargs when this check runs. It’s an unintended side effect of a change aimed at improving the API, where legitimate Streamlit-specific parameters were not properly distinguished from the Plotly configuration kwargs in the logic that triggers the warning. This creates a situation where developers are trying to follow the documentation for standard parameters, but are inadvertently flagged for using deprecated features. It's a classic case of an overly aggressive deprecation checker that needs fine-tuning to differentiate between Streamlit's own parameters and truly variable keyword arguments destined for the Plotly config dictionary. The core issue is that width and height, while directly used by st.plotly_chart, were not filtered out from the kwargs dictionary before the deprecation warning was issued, making the warning appear for valid Streamlit arguments.

Understanding the Underlying Code Change

To truly grasp why this st.plotly_chart deprecation warning is popping up, we need to look at the underlying code change in Streamlit. The user's provided context helpfully points to the specific logic that was introduced:

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 snippet is designed to detect any remaining keyword arguments (kwargs) after the function has processed its explicitly defined parameters. If kwargs is not empty, it triggers the deprecation warning. The issue arises because parameters like width and height, despite being legitimate, documented arguments for st.plotly_chart, are still being passed into the kwargs dictionary before this check is performed and without being explicitly consumed and removed from kwargs by the st.plotly_chart function itself. In essence, the function signature likely looked something like def plotly_chart(fig, ..., **kwargs):, where width and height should have been explicit arguments extracted before the kwargs check. When width="content" is passed, it falls into the **kwargs bucket. Then, the if kwargs: condition evaluates to True because width is still there, leading to the warning. This means the internal parsing logic for st.plotly_chart wasn't perfectly aligned with the deprecation warning implementation. The intention was likely to warn users who were passing Plotly-specific config options directly as kwargs (e.g., st.plotly_chart(fig, displayModeBar=False)), not those using Streamlit's own parameters. However, the current implementation inadvertently catches Streamlit’s own width and height parameters, which should have been handled separately or explicitly popped from the kwargs dictionary before the warning check. This is a classic case of an off-by-one or off-by-a-parameter error in the internal handling of arguments, causing legitimate usage to be flagged as deprecated. The developers likely intended for width and height to be processed as dedicated parameters, and only truly unrecognized or forwarded kwargs to trigger the warning. The regression arises because this specific warning mechanism was introduced or modified in a way that didn't fully account for width and height being directly consumed by st.plotly_chart as documented arguments, rather than being treated as arbitrary Plotly kwargs that should go into the config dictionary. This subtle oversight is what causes the discrepancy between expected behavior (no warning for documented parameters) and current behavior (warning for width="content").

Step-by-Step Guide to Reproduce and Verify: Catching the kwargs Warning in Action

Alright, let's roll up our sleeves and actually see this kwargs deprecation warning in action. Reproducing the issue is often the first and most critical step in understanding and, eventually, fixing it. This section will guide you through setting up a minimal Streamlit environment and running a simple Python script that will reliably trigger the warning. You don't need a complex setup; just a few lines of code will suffice to demonstrate the st.plotly_chart width="content" conundrum. By carefully following these steps, you'll gain firsthand experience with the problem, confirming that the warning appears even when you're using parameters as described in the official documentation. This hands-on approach is invaluable for troubleshooting and will prepare you for implementing potential workarounds or understanding future fixes.

Setting Up Your Streamlit Environment

Before we write any code, let's make sure your Python environment is ready for action. If you haven't already, you'll need to install Streamlit and Plotly. It's always a good practice to work within a virtual environment to keep your project dependencies isolated and clean. Open your terminal or command prompt and follow these simple instructions. First, create a virtual environment with python -m venv streamlit-plotly-env and then activate it. For macOS/Linux users, this means source streamlit-plotly-env/bin/activate, while Windows users will use streamlit-plotly-env\Scripts\activate. Once activated, install the necessary libraries using pip install streamlit plotly. It's a good idea to ensure you have a recent Streamlit version; the reported issue occurred on 1.50.0, so consider pip install streamlit --upgrade or targeting pip install streamlit==1.50.0. Finally, verify your Streamlit installation by running streamlit hello, which should launch a demo app in your browser. This careful setup ensures that our environment is clean and ready, allowing us to accurately observe the deprecation warning without interference from other packages or outdated versions.

The Reproducible Code Example Explained

Now that your environment is sparkling clean, let’s get to the core of the problem. We'll use the exact reproducible code example provided in the issue description. Create a new Python file, let's call it 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) # Note: These are Plotly's internal layout widths, not Streamlit's

# Display the Plotly chart using st.plotly_chart with Streamlit's width parameter
st.plotly_chart(fig, width="content")

Once you've saved app.py, open your terminal (with your virtual environment activated, if you used one) in the same directory as your file and run your Streamlit application:

streamlit run app.py

As soon as Streamlit loads the application and renders the st.plotly_chart component, you should see the infamous kwargs deprecation warning printed in your terminal. It will look something like this:

2023-XX-XX XX:XX:XX.XXX DeprecationWarning: 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 confirms that even when passing a documented Streamlit parameter like width="content", the st.plotly_chart function incorrectly flags it as a deprecated variable keyword argument intended for Plotly's internal configuration. The interesting part here is that we're not passing displayModeBar=False or any other Plotly configuration directly. We are explicitly using width="content", which is a Streamlit-specific argument designed to make the chart expand to the column's width. This behavior clearly demonstrates the regression: a valid, documented use of a Streamlit parameter is being erroneously caught by a deprecation warning intended for a different purpose. This hands-on reproduction helps solidify our understanding of the problem and sets the stage for discussing solutions and workarounds. The fact that the warning appears immediately upon rendering the chart underscores the immediate impact of this change on developer experience and the need for a clear resolution or guidance.

Expected vs. Current Behavior: A Closer Look at st.plotly_chart Anomalies

When we interact with any library or framework, we operate based on certain expectations derived from its documentation and previous experiences. For st.plotly_chart, this expectation is clear: documented parameters should work as advertised, without triggering unrelated warnings. However, the current situation presents a clear divergence between what developers expect and the current behavior observed, leading to confusion and unnecessary concern about deprecation. Let's really zero in on this discrepancy.

What We Expect When Using width="content"

From a developer's perspective, using width="content" with st.plotly_chart is a straightforward and highly beneficial way to ensure your Plotly visualizations adapt perfectly to the layout of your Streamlit application. The expected behavior is simple: the chart should automatically expand to occupy the full width of its containing column or element. This feature is a cornerstone of creating responsive and aesthetically pleasing dashboards, allowing charts to seamlessly integrate into various screen sizes and column configurations. We anticipate that by passing width="content", Streamlit will internally handle the sizing, making our charts look great without us needing to manually calculate pixel values or deal with complex responsive design logic. It streamlines the development process significantly, freeing us to focus on data insights rather than intricate styling. Furthermore, given that width is a documented parameter for st.plotly_chart, clearly specified in the official Streamlit API reference, we absolutely expect no deprecation warnings when using it. It's an explicit argument recognized and processed by Streamlit itself, designed specifically for controlling the display of the chart component within the Streamlit interface, not a generic or variable keyword argument meant for Plotly's internal config object. The purpose of width="content" is purely about Streamlit's rendering of the chart container, aligning it with other Streamlit layout options like st.columns or st.expander. Developers should be able to rely on official documentation without being penalized by warnings that don't apply to their specific, valid, and documented usage. This expectation is rooted in the fundamental principle of a stable and predictable API, where valid parameters don't cause erroneous warnings. We want to focus on building great data applications and delivering value to our users, not on deciphering unexpected system messages or wasting time investigating what appears to be a bug in our perfectly valid code. This discrepancy between documentation and actual warning behavior is what makes this issue particularly confusing and frustrating for the Streamlit community.

The Reality: Unintended kwargs Warnings

Now, let's confront the current reality. Despite our clear expectations and adherence to documentation, when we run the reproducible code with st.plotly_chart(fig, width="content"), we are met with a disconcerting DeprecationWarning. This warning 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 is where the unintended behavior surfaces. The warning message suggests that we are passing "variable keyword arguments" that should be moved into a config dictionary. However, width="content" is distinctly not a Plotly configuration option; it's a Streamlit-specific instruction. The problem, as we've discussed, stems from an internal implementation detail where the width parameter (and presumably height too) is inadvertently being caught by the generic kwargs detection logic before it's properly consumed and removed by the st.plotly_chart function. This means that even though Streamlit does process and apply width="content" to the chart's display, the warning mechanism incorrectly identifies width as an unrecognized kwarg that falls under the deprecation umbrella. This behavior is a clear regression because in previous Streamlit versions, using width="content" would not trigger such a warning. It worked silently and as expected. The introduction of this specific kwargs deprecation check, without sufficiently distinguishing Streamlit's own internal parameters from Plotly's configuration parameters, has led to this confusing and erroneous warning. Developers are left with a functional application but a noisy terminal, forced to either ignore a potentially important warning or spend time investigating what appears to be a false positive. This detracts from the developer experience and creates unnecessary friction, making it harder to identify actual deprecated kwargs if they were indeed being passed for Plotly configuration. The impact extends beyond just the warning itself; it can lead to developers being overly cautious or even avoiding certain documented parameters out of fear of future breakage, which limits the utility of the library. It’s a situation that truly highlights the delicate balance between API evolution and backward compatibility.

Why This Regression Matters for Streamlit Developers

This st.plotly_chart regression, where a valid, documented parameter triggers a deprecation warning, is more than just a minor inconvenience; it significantly impacts the Streamlit developer experience and raises questions about API reliability. For developers, warnings are critical signals. They indicate potential issues, suggest improvements, or alert us to upcoming breaking changes that require our attention. When a warning appears for perfectly valid and documented code, it creates a "cry wolf" scenario. Developers may start to distrust warnings altogether, leading them to miss actual important dep recations or critical issues in their applications. This noise makes debugging harder and reduces overall developer confidence in the framework's stability.

Firstly, it undermines the trust in Streamlit's documentation. If developers cannot rely on the documentation to guide correct usage without unexpected warnings, they might become hesitant to adopt new features or even continue using the platform. The documentation explicitly lists width as a parameter for st.plotly_chart, so encountering a deprecation warning when using it as specified is contradictory and confusing. This friction can slow down development cycles as developers spend time investigating phantom problems rather than focusing on their core tasks.

Secondly, it introduces unnecessary mental overhead. Every time a developer sees this warning, they have to consciously dismiss it, knowing it's a false positive. This constant mental filtering is inefficient and contributes to developer fatigue. In a fast-paced development environment, clarity and predictability are paramount. When the tools we use are inconsistent, it adds a layer of complexity that is entirely avoidable. This problem can also be particularly vexing for new users who are just learning Streamlit. They might assume they are doing something wrong, when in fact, the issue lies within the framework's internal warning mechanism. Such experiences can unfortunately deter new adopters, hindering the growth and wider acceptance of Streamlit.

Thirdly, this regression has implications for future-proofing Streamlit apps. The warning explicitly states that kwargs will be removed. While we know width should not be included in this, the persistent warning creates uncertainty. What if, in a future release, width is accidentally removed from the st.plotly_chart signature because it was incorrectly categorized as a kwarg in the deprecation process? Developers might feel compelled to refactor their code unnecessarily, moving width into a config dictionary where it doesn't belong, just to silence the warning. This would lead to incorrect architectural decisions and potentially break their applications if st.plotly_chart's internal handling of config doesn't interpret width correctly. It introduces a subtle but significant risk of misinterpreting the API's future direction based on misleading warnings.

Moreover, the warning itself suggests using the config argument for Plotly configuration options. This is indeed the correct future-proof approach for Plotly-specific kwargs. However, forcing Streamlit-specific parameters like width into config would be a semantic and functional mismatch. width="content" tells Streamlit how to draw the component, not Plotly how to render the plot. Mixing these concerns inappropriately would complicate the API further and make code less readable and maintainable. A clear distinction between Streamlit layout parameters and Plotly rendering parameters is essential for good design. This current behavior muddles that distinction, making it harder for developers to write clean, idiomatic Streamlit code. In essence, this regression affects not just the immediate user experience but also the long-term architectural stability and understanding of Streamlit applications, making it a critical issue that warrants a precise and timely resolution to restore confidence and streamline development.

How to Work Around This Issue (and Future-Proof Your Code)

While waiting for an official fix from the Streamlit team, developers need practical solutions to keep their applications running smoothly and their consoles free of distracting warnings. Addressing this st.plotly_chart deprecation warning requires understanding the intended API direction and applying clever workarounds for the current regression. The goal is not just to silence the warning, but to future-proof your Streamlit apps by adopting practices that align with the framework's evolving design philosophy.

One immediate and commonly sought-after workaround for parameters like width="content" is to leverage Streamlit's explicit container width capabilities. Since width="content" is intended to make the chart expand to its parent container, you can often achieve a similar effect by not passing width="content" directly to st.plotly_chart and instead relying on the natural flow of Streamlit's layout. If your st.plotly_chart is placed directly within a column or the main app body, it might naturally try to fill the available space without width="content".

However, the more robust and kwargs-warning-free approach for cases where width or height are not explicitly consumed by st.plotly_chart as direct, non-kwargs arguments, and you still need fine-grained control over the chart's display, is to rethink how you structure your layout. For instance, if you want a chart to always occupy the full width of its parent container, you can remove the width="content" argument from st.plotly_chart and instead manipulate the Plotly figure's layout to be responsive, or place the chart within a Streamlit container that implicitly handles the width. The Streamlit documentation often suggests that if use_container_width (the old way) or width="container" (the new way, conceptually similar to width="content") are explicitly handled, they shouldn't trigger the generic kwargs warning. The fact that width="content" does trigger it indicates the bug.

A common pattern for true Plotly configuration is to use the config parameter. For example, if you wanted to hide the Plotly mode bar, you'd use:

st.plotly_chart(fig, config={'displayModeBar': False})

This is the future-proof way for Plotly's internal configurations. But for width="content", this advice doesn't directly apply because width is a Streamlit display parameter, not a Plotly display setting.

The most direct workaround to silence the warning while maintaining the width="content" behavior, given the current bug, is a bit tricky. Since the issue is that width="content" is being mistakenly interpreted as a kwarg for Plotly's config, and if you absolutely need width="content"'s effect, the most immediate "fix" involves either:

  1. Ignoring the warning (with caution): If you understand why the warning appears (i.e., it's a false positive for a documented parameter), you might choose to live with it until a patch is released. This isn't ideal for clean logs, but it allows your app to function.
  2. Using use_container_width=True if still supported (check Streamlit version): Before width="content" was fully integrated, use_container_width=True was the way to go. If your Streamlit version still supports this without triggering the kwargs warning, it might be a temporary alternative. However, this is also subject to its own deprecation cycle.
  3. Refactor your layout to avoid width="content" if possible: If the goal is just to have the chart fill its parent, sometimes simply not passing width="content" and letting Streamlit's default layout behavior take over can work, especially if the chart is in a top-level container or column. For instance, if you define col1, col2 = st.columns(2) and put st.plotly_chart(fig) in col1, it will naturally fill col1. This method relies on Streamlit's responsive container behavior rather than explicit width parameter passing.

The ideal solution is for Streamlit to fix the internal logic of st.plotly_chart so that its own documented width and height parameters are consumed before the generic kwargs deprecation check is performed. Until then, carefully evaluating if you truly need width="content" or if Streamlit's default container behavior suffices, and otherwise being aware of the warning's context, are your best bets. For actual Plotly configuration, always lean on the config argument to ensure your code remains robust and clear for the long haul. Remember, this problem is a known regression, so a fix is likely in the pipeline. Keeping your Streamlit library updated will be crucial.

Conclusion: Navigating Streamlit's Evolving API with Confidence

We've journeyed through the intricacies of the st.plotly_chart kwargs deprecation warning, particularly focusing on its unexpected appearance when using the width="content" parameter. It's clear that while the underlying intention of Streamlit's API evolution is to provide a more structured and robust way to handle Plotly configurations, the current implementation inadvertently flags legitimate Streamlit-specific parameters as deprecated kwargs. This regression impacts developer experience, erodes trust in documentation, and introduces unnecessary confusion for an otherwise straightforward function. Understanding that this warning is a false positive for width="content" (and similar Streamlit-specific dimension parameters) is the first step towards navigating this issue with confidence.

As developers, our responsibility is to stay informed about API changes and adapt our code to align with best practices. While this particular warning is a bug, the broader message about consolidating Plotly-specific options into the config argument is a valid and future-proof design principle. For any true Plotly configurations you might need (like disabling the mode bar, enabling scroll zoom, or setting static plots), the config dictionary is indeed the place to put them. This keeps your code clean, explicit, and less prone to breaking changes as both Streamlit and Plotly continue to develop. For the width="content" specific case, until a patch is released, evaluating whether the argument is strictly necessary or if Streamlit's default container responsiveness can achieve the desired layout effect is a pragmatic approach. If width="content" remains critical for your specific layout needs, understanding the warning's context allows you to acknowledge it as a known regression rather than a critical flaw in your own code.

The Streamlit community is vibrant and responsive, and issues like this are often addressed swiftly once identified. Staying updated with the latest Streamlit releases is always a good strategy to benefit from bug fixes and performance improvements. By actively engaging with the documentation, testing your applications, and paying attention to official announcements, you can ensure your Streamlit dashboards remain cutting-edge and reliable. Let's continue building amazing things with Streamlit, armed with a deeper understanding of its nuances and the confidence to troubleshoot unexpected warnings! The journey of software development is one of continuous learning and adaptation, and mastering such intricacies makes us better engineers.

For further reading and keeping up-to-date with Streamlit and Plotly, consider exploring these resources:

  • Streamlit Documentation: Always the first stop for official API details and guides. You can find comprehensive information on st.plotly_chart and other components there.
  • Plotly Python Graphing Library Documentation: Dive deep into Plotly's vast capabilities and configuration options. Understanding Plotly's config object will be particularly helpful for advanced customizations.
  • Streamlit Community Forum: A great place to discuss issues, get help, and share your projects with other Streamlit users and developers. It's an excellent resource for real-time problem-solving and staying informed about community discussions.