Streamlit Plotly Chart: Avoid Deprecation Warnings

by Alex Johnson 51 views

When you're building interactive dashboards with Streamlit and leveraging the power of Plotly for stunning visualizations, you want a smooth experience. Recently, a few users have encountered a puzzling deprecation warning when using the st.plotly_chart function, specifically when setting the width or height to "content". This warning pops up even when you're not explicitly passing any variable keyword arguments (kwargs) and are sticking to the documented parameters. It's a bit like getting a "check engine" light when your car is running perfectly fine – confusing and a little concerning. This article dives deep into this specific issue, explains why it's happening, and most importantly, how you can easily resolve it to ensure your Streamlit apps run without any unnecessary warnings.

Understanding the kwargs Deprecation Warning in st.plotly_chart

Let's get straight to the heart of the matter: the kwargs deprecation warning in Streamlit's st.plotly_chart. You might be scratching your head, wondering, "But I'm not using **kwargs! I'm just setting width='content'!" You're absolutely right, and that's precisely where the confusion lies. The warning message itself can be a little misleading because it broadly refers to "variable keyword arguments." The intention behind this change in Streamlit was to guide users towards a more structured way of passing configuration options to Plotly charts. Previously, developers might have passed various Plotly-specific configurations directly as keyword arguments to st.plotly_chart, which could lead to conflicts or ambiguities as Streamlit evolved.

To address this, Streamlit introduced the config argument. This config argument is a dictionary where you can place all your Plotly-specific configurations, keeping them neatly organized and separate from Streamlit's own function parameters. This approach offers several benefits: it enhances clarity, prevents potential clashes between Streamlit and Plotly parameters, and makes your code more maintainable. However, the implementation of this deprecation warning seems to be a bit overzealous. It's catching cases where width='content' or height='content' are used, which are legitimate and documented parameters for controlling the chart's dimensions. These parameters are not arbitrary kwargs but rather specific arguments intended for layout control.

The core of the problem lies in how Streamlit's st.plotly_chart function internally handles its arguments. When you pass width='content', Streamlit might be interpreting this, at some level of its internal processing, in a way that triggers the general kwargs warning logic. This is likely an unintended consequence of the way the deprecation was implemented, aiming to catch truly dynamic or unspecified keyword arguments rather than pre-defined layout options. The goal was to encourage the use of the config dictionary for Plotly settings, but in this instance, it's incorrectly flagging a standard layout parameter.

The good news is that this is usually not a fundamental bug in your code or a sign that your plot will break. It's more of an informational message that's being displayed a bit too broadly. You're still able to achieve the desired layout for your charts. The challenge is understanding why this warning appears and how to suppress it if it's causing unnecessary noise in your development workflow.

The deprecation warning is a signal that the way certain arguments are handled is changing. For st.plotly_chart, Streamlit wants to encourage a cleaner separation of concerns. Instead of passing Plotly's layout options directly into st.plotly_chart as if they were Streamlit arguments, they should ideally be placed within the config dictionary. This includes things like responsive, displayModeBar, and other Plotly-specific settings. However, the width and height parameters, especially when set to "content", are Streamlit-specific ways to control how the chart fits within the app's layout, not necessarily Plotly's internal rendering configuration. The warning's logic is catching these in a way that suggests they are being passed as general kwargs, which isn't the case.

To summarize, the warning is a side effect of a broader change aimed at improving argument handling. While the intention is good – promoting cleaner code and better integration – the implementation is currently flagging legitimate use cases of the width and height parameters. This is a common scenario in software development where a feature designed to improve things can sometimes have unintended side effects that need to be ironed out.

Reproducible Example and Debugging the Warning

To truly understand an issue, it's crucial to have a clear, reproducible example. The provided code snippet perfectly illustrates the scenario:

import plotly.graph_objects as go
import streamlit as st

fig = go.Figure()
fig.add_trace(go.Barpolar(r=[1], theta=[0], width=[120]))
fig.update_layout(width=500, height=360)

st.plotly_chart(fig, width="content")

When you run this code with Streamlit version 1.50.0 (or potentially around that version), you'll see the deprecation warning pop up, even though width="content" is a documented and valid way to tell Streamlit to size the Plotly chart to fit its container.

Let's break down why this happens based on the information available. Streamlit's internal st.plotly_chart function has undergone changes to manage its arguments more robustly. Part of this involves a check for kwargs (keyword arguments that aren't explicitly defined parameters of the function). The code snippet that likely triggers the warning looks something like this:

# Simplified representation of the logic that might be causing the warning
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."
    )

The issue arises because Streamlit's argument parsing might be treating width="content" as if it falls into the kwargs category, even though width is intended as a specific layout parameter. This isn't ideal because width and height control how the chart behaves within the Streamlit app's layout, not necessarily how the Plotly figure itself is configured internally. Plotly itself has parameters like layout.width and layout.height, but Streamlit's width and height parameters on st.plotly_chart are about controlling the display area for the chart within the Streamlit page.

_To debug this effectively, you'd typically do the following:__

  1. Isolate the Problem: As demonstrated, the reproducible code is key. If you remove width="content" and use a fixed pixel value (e.g., width=500), does the warning disappear? If it does, it strongly suggests the issue is tied to the "content" value or how Streamlit handles dynamic sizing.
  2. Check Streamlit Version: The issue was reported with Streamlit 1.50.0. Verifying if the warning persists in newer versions (e.g., 1.51.0, 1.52.0, etc.) is crucial. Often, such issues are quickly identified and patched by the Streamlit team. You can check the latest Streamlit releases and their changelogs.
  3. Examine config Argument: While the warning is about kwargs, it's good practice to ensure you're not accidentally passing Plotly configuration items here. If you were to pass Plotly settings, they should go into the config dictionary. For example:
    st.plotly_chart(fig, config={'responsive': True})
    This doesn't directly solve the width='content' warning, but it's the recommended way to handle Plotly configurations moving forward.
  4. Look for Updates: Since this was reported as a regression, it indicates that this functionality used to work without warnings in a previous version. This suggests a change in Streamlit's internal argument handling is the culprit. Checking the Streamlit GitHub repository for open issues or recent pull requests related to st.plotly_chart and argument handling would be a good next step.

By systematically going through these debugging steps, you can confirm the behavior and prepare to apply a solution or wait for an official fix.

Expected vs. Current Behavior: Clarifying the Discrepancy

It's essential to distinguish between what we expect to happen and what's actually occurring. In the context of Streamlit's st.plotly_chart, the expected behavior when using the width="content" parameter is quite straightforward: the Plotly chart should render and automatically adjust its width to fill the available space within its container on the Streamlit page. This is a highly desirable feature for creating responsive web applications where content should adapt gracefully to different screen sizes. The documentation for Streamlit typically guides users to leverage such parameters for intuitive layout management. Therefore, one would reasonably expect that using a documented parameter like width="content" would simply work as intended, without any accompanying warnings.

However, the current behavior, as reported, deviates from this expectation. When width="content" (or height="content") is used, users are presented with a 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 warning is problematic for a couple of reasons. Firstly, as mentioned, the user isn't explicitly passing arbitrary kwargs. They are using a specific, documented parameter intended for layout control. Secondly, the warning suggests migrating to the config argument, which is primarily for Plotly-specific visual configurations (like responsive, displayModeBar, etc.), not for controlling the display area of the chart within the Streamlit app. This can lead users down the wrong path, making them believe they need to configure responsiveness within the config dictionary when the width="content" parameter itself is meant to achieve that within Streamlit's layout system.

This discrepancy highlights a potential misinterpretation or overly broad application of the kwargs deprecation logic within Streamlit's st.plotly_chart function. The system seems to be flagging parameters that are not truly arbitrary kwargs but are, in fact, well-defined arguments for controlling how the chart is rendered within the Streamlit environment. The warning message, while generally useful for guiding developers towards best practices for Plotly configurations, is being triggered incorrectly in this specific scenario.

The core issue is that Streamlit's internal argument handling for st.plotly_chart is not correctly differentiating between arbitrary keyword arguments and its own set of specific, documented parameters like width and height. The deprecation warning is designed to catch unhandled kwargs to encourage the use of the config dictionary for Plotly settings. However, when width='content' is passed, it's being erroneously caught by this kwargs check, leading to the misleading warning. This is a classic case of a feature intended to improve code quality having an unintended side effect on legitimate use cases.

Expected Behavior Summary:

  • st.plotly_chart(fig, width="content") should render the chart filling its container without any warnings.

Current Behavior Summary:

  • st.plotly_chart(fig, width="content") renders the chart but displays a deprecation warning about kwargs.

This clear distinction between expected and current behavior is crucial for developers and for the Streamlit team to identify and address the problem effectively. It confirms that the functionality is present but marred by an inaccurate warning message.

Is this a Regression?

The user explicitly stated, "Yes, this used to work in a previous version." This is a critical piece of information, confirming that the behavior observed is indeed a regression. A regression means that a feature or functionality that was working correctly in an earlier version of the software has stopped working or started behaving incorrectly in a newer version. In this case, the ability to use st.plotly_chart with width="content" (or height="content") without triggering a kwargs deprecation warning was present in older versions of Streamlit but is now causing an unwanted warning.

Understanding that this is a regression helps pinpoint the cause. It strongly suggests that a recent change in Streamlit's codebase, likely related to how arguments are parsed or how deprecation warnings are issued for st.plotly_chart, is responsible. Developers can then focus their investigation on the commits or pull requests that were made around the time this functionality broke. This is invaluable for bug fixing, as it narrows down the search space considerably.

When a regression is identified, it often means that the implementation of a new feature or a refactoring effort inadvertently broke existing functionality. The introduction of the kwargs deprecation warning, aimed at improving code structure, seems to have had an unintended consequence on how specific layout parameters are handled. The developers responsible for the change might not have anticipated that parameters like width='content' would be incorrectly categorized as generic kwargs by the new warning logic.

_Identifying this as a regression is key for several reasons:__

  1. Prioritization: Regressions are often high-priority issues for software maintainers because they indicate a step backward in stability and user experience. Users expect that updating software won't break things that previously worked.
  2. Root Cause Analysis: It directs the debugging efforts toward recent code changes rather than searching for a flaw in a long-standing feature.
  3. User Trust: Acknowledging and fixing regressions is vital for maintaining user trust in the software's reliability.

In summary, the confirmation that this behavior is a regression is a significant clue. It tells us that the issue is not inherent to the design of st.plotly_chart or the use of width='content', but rather a consequence of recent modifications within Streamlit itself. This is good news for the user community, as regressions are typically addressed more urgently than novel feature bugs.

Moving Forward: Solutions and Best Practices

While the Streamlit team works on a potential fix for this specific regression, there are practical ways to manage or work around the kwargs deprecation warning when using st.plotly_chart with width="content" or height="content". The primary goal is to ensure your Streamlit application functions correctly and delivers the desired visualizations without unnecessary noise from warnings.

1. Explicitly use the config argument for Plotly settings:

As the warning suggests, any Plotly-specific configurations should be placed within the config dictionary. While width='content' isn't a Plotly config in this context, other common settings like responsive: True (which might seem related but is a Plotly-specific setting) should indeed go here. This adheres to the spirit of the deprecation notice.

import plotly.graph_objects as go
import streamlit as st

fig = go.Figure()
fig.add_trace(go.Barpolar(r=[1], theta=[0], width=[120]))
fig.update_layout(width=500, height=360)

# Use the config dictionary for Plotly-specific configurations
# Note: 'responsive': True is a Plotly setting, not a Streamlit setting.
# The width='content' issue is separate from this.
st.plotly_chart(fig, config={'responsive': True})

While this doesn't directly solve the width='content' warning, it's good practice and ensures you're using the recommended approach for other Plotly configurations.

2. Consider alternative layout management (if "content" is the issue):

If the "content" value is indeed what's triggering the warning, and you need precise control, you might need to define a fixed width or height. However, this defeats the purpose of responsive design. A better approach might be to ensure the parent container in Streamlit is set up correctly.

import streamlit as st
import plotly.graph_objects as go

# Example using columns to manage layout
col1, col2 = st.columns(2)

fig = go.Figure()
fig.add_trace(go.Barpolar(r=[1, 2, 3], theta=[0, 90, 180]))

# You can still pass width and height, but note the warning persists for "content"
# If you were to use fixed values, the warning might not appear.
with col1:
    st.plotly_chart(fig, width="content") # Warning may still appear here

with col2:
    st.plotly_chart(fig, height=300) # Fixed height, warning less likely if width isn't 'content'

This demonstrates that the warning is tied to the specific use of width="content" or height="content". If your layout requires exact sizing, you might opt for pixel values, but this is generally not recommended for responsive apps.

3. Update Streamlit:

As this was identified as a regression, the Streamlit team is likely aware of it. The most straightforward solution is often to update to the latest available version of Streamlit. Check the official Streamlit documentation or their GitHub repository for the most recent releases.

pip install --upgrade streamlit

It's highly probable that a future release will address this specific instance where documented parameters are incorrectly triggering the kwargs deprecation warning.

4. Report the Issue (if not already fixed):

If you've updated and the issue persists, or if you want to ensure it's on the Streamlit team's radar, consider opening an issue on the Streamlit GitHub repository. Provide the reproducible code example and clearly state that it's a regression. This helps the maintainers understand the impact and prioritize the fix.

In conclusion, while the kwargs deprecation warning for st.plotly_chart can be confusing when using width="content", understanding its likely cause as a regression in argument handling is key. By adhering to best practices for the config argument and staying updated with Streamlit releases, you can effectively navigate this issue and maintain clean, functional data applications.

For further reading on Plotly configurations and best practices within Streamlit, I recommend checking out the official Streamlit documentation on displaying elements and the Plotly documentation on configuration options. These resources can help you optimize your visualizations and understand the interaction between Streamlit and Plotly more deeply.