Streamlit: Fix Plotly Chart Kwargs Deprecation Warning

by Alex Johnson 55 views

Hey there, data visualization enthusiasts! Have you ever been happily coding away in Streamlit, creating some awesome interactive charts with Plotly, only to be met with a cryptic kwargs deprecation warning? It can be a bit puzzling, especially when you're pretty sure you're just using the documented parameters. Well, you're not alone, and we're here to shed some light on this particular quirk. This article dives deep into why this warning pops up, even when you're not explicitly passing variable keyword arguments, and how to navigate it like a pro.

Understanding the st.plotly_chart Kwargs Deprecation Warning

The plotly_chart kwargs deprecation warning in Streamlit is designed to gently guide developers towards a more robust and future-proof way of passing configuration options to Plotly charts embedded within Streamlit applications. At its core, this warning signals a shift in how Streamlit handles the arguments passed to the st.plotly_chart function. Previously, it was more permissive, allowing a wider range of arguments, including those that might not be directly recognized or intended for the Streamlit wrapper itself, to be passed through to the underlying Plotly figure. This flexibility, while convenient in some cases, could lead to subtle issues, unexpected behavior, or difficulties in Streamlit's internal management of the chart's rendering and configuration. The warning essentially says, "Hey, we're streamlining how you configure Plotly charts. Instead of passing arbitrary keywords that might cause confusion, please use the dedicated config argument for Plotly-specific settings." This makes it clearer for both the developer and Streamlit itself exactly what's being configured and how. It’s all about enhancing clarity and maintainability within your Streamlit apps. By consolidating Plotly configurations within the config dictionary, you create a more organized structure, making your code easier to read, debug, and adapt as Streamlit and Plotly evolve. This proactive approach from the Streamlit team helps prevent potential conflicts and ensures that your visualizations remain consistent and reliable across different versions. It’s a small change that contributes to a larger goal of creating a more predictable and stable development environment for interactive data storytelling.

Why Does the Warning Appear Even Without Explicit Kwargs?

This is where things get a little nuanced, and it's the root of the confusion for many users. The plotly_chart kwargs deprecation warning can appear even when you're not explicitly passing **kwargs in your Python code. The warning message, as observed in recent Streamlit versions (like 1.50.0), is triggered by the presence of any keyword arguments that Streamlit interprets as potentially being passed down to Plotly in a way that's now discouraged. This includes arguments like width or height when they are set to values like 'content'. Streamlit's internal handling of these parameters has evolved. What used to be a direct pass-through of arguments to Plotly might now be intercepted or managed differently by Streamlit to ensure compatibility and a consistent user experience. The warning is thrown because the code that handles st.plotly_chart checks if there are any remaining keyword arguments after it has processed its own documented parameters. If width='content' or height='content' are passed, Streamlit might be treating these as part of a broader category of arguments that could potentially be misused as generic kwargs. The warning is a safeguard, indicating that while these specific arguments might currently work, the mechanism through which they are processed is being deprecated. The recommended approach is to use the config argument for Plotly-specific settings, including dimensions if they are to be controlled via Plotly's configuration rather than Streamlit's layout system. This is a subtle but important distinction: the warning isn't necessarily about you passing **kwargs incorrectly, but about Streamlit's internal processing of certain arguments that could be part of a broader, now-deprecated kwargs handling strategy. It's an attempt to steer users towards the config dictionary for all Plotly-related configurations, even those that seem straightforward like setting a width. This aims to future-proof your applications, ensuring they continue to function smoothly as Streamlit updates.

Reproducible Example: The width='content' Scenario

Let's walk through a reproducible code example that clearly demonstrates the plotly_chart kwargs deprecation warning when using width='content'. This example is straightforward and mirrors the scenario described by users encountering this issue:

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) # These are layout settings, not direct args to st.plotly_chart

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

In this snippet, we first import the necessary libraries: plotly.graph_objects for creating the figure and streamlit for the web application framework. We then construct a basic go.Figure with a Barpolar trace. Notice that fig.update_layout(width=500, height=360) sets dimensions within the Plotly figure itself. However, the critical part is the call to st.plotly_chart(fig, width="content"). Here, we are passing width="content" directly as an argument to st.plotly_chart. According to Streamlit's documentation, this is a valid way to tell the chart to adapt its width to the container's content. Despite being a documented and intended use of the st.plotly_chart function, this specific argument, when present, triggers the deprecation warning. The warning message typically 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 highlights the core issue: Streamlit's internal logic for handling arguments like width='content' is being caught by the broader check for deprecated keyword argument usage, even though width itself isn't a variable keyword argument in the typical Python sense, and 'content' is a documented value.

The Shift Towards the config Argument

Streamlit's decision to introduce the config argument for st.plotly_chart is a strategic move aimed at streamlining Plotly integration and ensuring better compatibility with future updates. The previous approach, where various arguments could be passed directly, was functional but lacked a clear structure for handling Plotly-specific configurations. This often led to ambiguity about which arguments were for Streamlit and which were for Plotly. By consolidating these settings into a single config dictionary, Streamlit provides a centralized and explicit way to manage all Plotly-related configurations. This not only cleans up the function signature but also makes it easier for developers to understand and manage the various options available for their Plotly charts. The config argument is essentially a dictionary that you pass to st.plotly_chart, and within this dictionary, you can include any valid Plotly configuration options. This includes display modes, behaviors, and even layout adjustments that are specific to Plotly's rendering engine.

Why config is the Future for Plotly Settings

The plotly_chart kwargs deprecation warning is a nudge towards adopting the config argument for a good reason: it offers a cleaner, more organized, and more future-proof way to manage Plotly chart settings within Streamlit. When you pass arguments directly to st.plotly_chart that are intended for Plotly's internal configuration, it can become unclear whether Streamlit is interpreting them or passing them through. This ambiguity can lead to unexpected behavior, especially as both Streamlit and Plotly libraries are updated independently. The config argument acts as a dedicated Plotly configuration hub. Instead of scattering settings across different parameters of st.plotly_chart, you can now group all Plotly-specific options within this single dictionary. This includes things like scrollZoom, displaylogo, modeBarButtonsToRemove, and importantly for the reported issue, options related to sizing and layout that are controlled by Plotly itself. For instance, if you want to control the responsiveness or specific dimensions that Plotly handles, you would look into what Plotly's layout or config options offer. By directing users to use config, Streamlit is establishing a clear contract: Streamlit handles its own arguments (like use_container_width which is now width), and Plotly handles its internal configurations via the config dictionary. This separation of concerns makes the codebase more robust and easier to maintain. It also means that as Plotly introduces new configuration options, your Streamlit apps can adopt them more seamlessly by simply updating the config dictionary, without waiting for Streamlit to expose each new Plotly option individually. This is a crucial step for maintaining parity with Plotly's advanced features.

How to Use the config Argument Effectively

To effectively use the config argument and avoid the plotly_chart kwargs deprecation warning, you need to understand how to structure the dictionary you pass. The config parameter in st.plotly_chart is designed to accept a Python dictionary containing various Plotly configuration options. Many of the settings that were previously passed as direct keyword arguments, or that control Plotly's behavior, can now be placed within this dictionary. For example, if you previously used st.plotly_chart(fig, use_container_width=True), this functionality is now largely handled by Streamlit's width and height parameters. However, for Plotly-specific behaviors, the config dictionary is your go-to. Let's say you want to disable the Plotly logo or remove certain mode bar buttons. You would do this by passing a dictionary like this:

config_options = {
 "scrollZoom": True, # Example: Enable scroll zoom
 "displaylogo": False, # Example: Hide the Plotly logo
 "modeBarButtonsToRemove": ["zoom2d", "pan2d", "autoScale2d", "resetScale2d"]
}

st.plotly_chart(fig, config=config_options)

For the specific issue of width and height, while Streamlit's width and height arguments handle the container's aspect, if you need to pass Plotly-internal sizing hints or behaviors, they might go into config. However, the warning specifically arises when using width='content' directly as an argument to st.plotly_chart, not within config. The resolution for that particular warning involves understanding that width='content' is a Streamlit-level adjustment. The deprecation warning is triggered because Streamlit's internal mechanism for handling that specific argument is being refactored to align with the new config approach for Plotly internals. Therefore, while you might not explicitly put width='content' inside the config dictionary, the warning is a signal that Streamlit is moving away from accepting such arguments directly and encouraging a more unified configuration approach, even if the exact parameters don't map 1:1 into the config dictionary for all cases.

Resolving the st.plotly_chart Deprecation Warning

So, how do we actually get rid of that pesky plotly_chart kwargs deprecation warning and ensure our Streamlit apps are up-to-date? The solution involves understanding Streamlit's evolving API for handling Plotly charts and aligning our code with the recommended practices. It's not always about finding a direct replacement for every keyword argument within the config dictionary, but rather about correctly utilizing Streamlit's own parameters and understanding where Plotly's configurations truly lie.

Updated Code Example and Best Practices

Let's revisit the reproducible code example and show how to adjust it to avoid the warning, incorporating best practices. The key is to rely on Streamlit's primary arguments for layout control and use config for Plotly's internal behaviors.

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]))
# Note: Layout width/height are often overridden by Streamlit's display
# fig.update_layout(width=500, height=360) 

# --- Resolution --- 
# The 'width="content"' argument is handled by Streamlit itself.
# The deprecation warning is triggered by Streamlit's internal processing
# of arguments that might have previously been treated as generic kwargs.
# To avoid the warning, ensure you are using documented parameters correctly.
# For this specific case, 'width="content"' IS a documented parameter,
# and the warning might be a bug or an overly broad check in Streamlit.
# However, for other Plotly-specific settings, use the 'config' argument.

# If the warning persists with width="content", it might be necessary to
# rely on Streamlit's default behavior or explicitly set width/height
# if Plotly's internal config doesn't offer the desired result.

# A common way to handle sizing is via Streamlit's layout:
# st.columns, st.container, st.expander, etc.
# Or directly using width/height arguments if they are officially supported
# and not causing warnings.

# Let's try passing it without the problematic width='content' first, 
# relying on Streamlit's default responsive behavior or explicit height/width
# if needed for the figure object itself.

# Option 1: Rely on Streamlit's default responsiveness
# st.plotly_chart(fig)

# Option 2: Explicitly setting height and letting width be responsive (if width="content" is truly problematic)
st.plotly_chart(fig, height=360)

# Option 3: If you need specific Plotly internal configs, use the config argument
# config_options = {
#  "scrollZoom": True,
#  "displaylogo": False
# }
# st.plotly_chart(fig, height=360, config=config_options)

# Based on the original report, `width='content'` *itself* triggers the warning.
# This suggests a potential issue in Streamlit's warning logic for this specific argument.
# The 'Expected Behavior' implies that `width='content'` *should not* cause a warning.
# If that's the case, and it *does* cause a warning, it points to a bug.
# The best practice then is to use arguments that don't trigger the warning,
# or to report the bug.

# For demonstration, let's show how to use configuration options if needed:
plotly_config = {
    "displaylogo": False,
    "modeBarButtonsToRemove": ["zoom2d", "pan2d", "lasso2d", "autoScale2d", "resetScale2d"]
}
st.plotly_chart(fig, height=400, config=plotly_config)

Best Practices Summary:

  1. Prioritize Streamlit's Layout Arguments: For controlling the overall size and placement of your chart within the Streamlit app, use Streamlit's layout components (st.columns, st.container, st.expander) and the direct width and height parameters of st.plotly_chart if they are documented and stable. The issue suggests width='content' might be hitting a warning trigger unexpectedly.
  2. Use config for Plotly Internals: Any settings that directly control Plotly's behavior, interactivity, or display features (like scrollZoom, displaylogo, modeBarButtonsToRemove) should be placed within the config dictionary.
  3. Stay Updated: Keep your Streamlit library updated. Warnings like these often indicate upcoming changes or are resolved in newer versions. The fact that this was reported as a regression suggests it might be a bug introduced in a recent update that will be fixed.
  4. Report Bugs: If a documented and expected feature (like width='content') consistently triggers a deprecation warning, consider filing an issue on the Streamlit GitHub repository. This helps the developers identify and fix such discrepancies.

Regression Analysis: Why Did This Stop Working?

This particular plotly_chart kwargs deprecation warning is indeed flagged as a regression, meaning it worked as expected in a previous version of Streamlit. This often happens when library maintainers refactor internal code to improve performance, add new features, or prepare for future changes. In this case, the warning seems to stem from changes made to how st.plotly_chart processes its arguments, particularly around the handling of keyword arguments that could be passed to Plotly. The introduction of the config parameter was likely part of a larger effort to create a more structured API. During this refactoring, the detection mechanism for