Streamlit Plotly Chart Width Issue: Deprecation Warning

by Alex Johnson 56 views

Hey there, fellow data enthusiasts and Streamlit aficionados! Have you ever been working on a slick dashboard, only to be interrupted by a mysterious deprecation warning when using st.plotly_chart? You're not alone! It turns out that even when you're diligently using the documented parameters like width="content" or height, Streamlit might be throwing a little warning your way about kwargs. Let's dive into what's happening and why this might be a bit of a head-scratcher.

The kwargs Conundrum in st.plotly_chart

So, you've got your beautiful Plotly chart, and you want to make sure it fits perfectly in your Streamlit app. You've read the docs, and you know that parameters like width="content" are the way to go for responsive sizing. You implement it, hit refresh, and then BAM! A deprecation warning pops up, something along the lines of "Variable keyword arguments for st.plotly_chart have been deprecated...". The funny thing is, you're not explicitly passing any variable keyword arguments yourself! You're just using the parameters that are clearly laid out in the documentation. This can be a bit confusing, right? It feels like Streamlit is scolding you for doing exactly what it told you to do. This particular issue seems to have surfaced prominently around Streamlit version 1.50.0 and has been identified as a regression, meaning it worked fine in earlier versions. The core of the problem lies in how Streamlit internally checks for and handles keyword arguments (kwargs) passed to the st.plotly_chart function. Even when parameters like width or height are passed as documented arguments, the internal logic might be misinterpreting their presence or how they are handled, triggering the deprecation warning as if a general, undocumented kwargs were passed. This is particularly frustrating because it can obscure other, potentially more important, warnings or errors in your application, and it creates unnecessary noise in your development workflow. The goal of good API design is to provide clear, predictable behavior, and this warning, when it appears without a clear cause from the user's perspective, undermines that goal. It's a sign that the internal implementation might need a closer look to ensure that documented parameters are correctly distinguished from true variable keyword arguments that are being deprecated. The hope is that this will be addressed in future updates, leading to a smoother experience for all Streamlit developers.

Why This Warning Matters

Now, you might be thinking, "It's just a warning, what's the big deal?" Well, while it might not break your app today, this kind of warning can be problematic for several reasons. Firstly, it creates unnecessary noise. When you see a warning, you naturally want to investigate it. If you can't find a clear cause in your own code, it can lead to a lot of wasted time trying to figure out what's going on. Secondly, it can mask other issues. If you have a real warning or error lurking in your code, a flood of these spurious kwargs warnings could make it harder to spot. Thirdly, it points to a potential inconsistency between the documentation and the actual behavior of the component. Good documentation is key to a smooth developer experience, and when the code doesn't quite align with what the docs say, it can erode confidence. The developers of Streamlit are aware of this issue, and it's been noted as a regression, indicating that it's something they intend to fix. The aim is to ensure that the st.plotly_chart function correctly interprets the arguments passed to it, differentiating between intentionally set parameters (like width="content") and actual, unintended variable keyword arguments. When this is resolved, we can expect a cleaner console output and a more streamlined debugging process, allowing us to focus on building amazing data applications without unnecessary distractions.

Reproducible Code Example: Seeing the Warning in Action

To help everyone understand and reproduce this issue, here's a simple code snippet that demonstrates the problem. This example uses streamlit and plotly.graph_objects to create a basic chart and then displays it using st.plotly_chart with the width="content" argument.

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 in a Streamlit environment (especially with versions around 1.50.0), you should see the deprecation warning appear in your console or Streamlit log output, even though you're using the documented width parameter. This clearly illustrates the unexpected behavior. The warning itself, as mentioned in the original report, often looks like this: 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 key here is that the warning is triggered despite the explicit use of a documented argument. This suggests that the internal mechanism checking for kwargs might be overly sensitive or not correctly parsing the arguments passed to st.plotly_chart. It's a small detail, but for developers striving for clean code and efficient debugging, it's a detail that matters. We're hoping for a fix that ensures only genuine, unintended kwargs trigger this warning, leaving the use of parameters like width and height unflagged.

Steps to Reproduce

  1. Ensure you have the necessary libraries installed:
    pip install streamlit plotly
  2. Save the reproducible code provided above as a Python file (e.g., app.py).
  3. Run the Streamlit application from your terminal:
    streamlit run app.py
  4. Observe the output: You should see the Plotly chart rendered in your browser, and importantly, a deprecation warning related to kwargs will appear in your terminal or the Streamlit log output.

This straightforward process allows anyone to verify the issue and understand the behavior reported. The simplicity of the steps underscores how easily this warning can be triggered, highlighting its nature as a potential bug or unintended consequence of recent changes in Streamlit's argument handling for st.plotly_chart.

Expected vs. Current Behavior

Let's be clear about what we expect and what's actually happening. When Streamlit introduced changes to how arguments are handled, particularly the transition from use_container_width to the more flexible width and height arguments, the expectation was a smoother experience.

Expected Behavior:

We expect that using documented parameters like width="content" or height with st.plotly_chart should function as intended without triggering any deprecation warnings related to kwargs. The warning about kwargs should only appear when a user passes genuinely undocumented or variable keyword arguments that are not part of the function's defined signature or intended use. The transition to the width argument was meant to be a clear improvement, and it should not come with the baggage of spurious warnings.

Current Behavior:

Currently, as observed, the st.plotly_chart function, particularly in versions around 1.50.0, issues a deprecation warning even when width="content" is used. This warning, often related to "Variable keyword arguments," is triggered even though the developer is using a documented parameter. The code snippet provided demonstrates this: st.plotly_chart(fig, width="content") results in the warning. This indicates that the internal logic responsible for detecting kwargs is too broad and is incorrectly flagging documented parameters as problematic.

This discrepancy is the crux of the issue – the warning is misleading, causing confusion and potentially masking real problems. It's a regression because this behavior wasn't present in earlier, stable versions of Streamlit, where using width="content" was a non-event in terms of warnings.

Is This a Regression?

Yes, this is indeed a regression. The behavior described – receiving a deprecation warning about kwargs when using documented parameters like width="content" in st.plotly_chart – was not present in previous stable versions of Streamlit. Developers could previously utilize these parameters without encountering such warnings. The fact that this functionality, which was previously working without issue, now triggers a warning indicates a change in the codebase that has negatively impacted the user experience. Regressions are particularly important to address because they can disrupt existing applications and workflows that relied on the previous, stable behavior. Identifying and fixing regressions helps maintain the reliability and trustworthiness of the Streamlit platform.

Debug Information

To aid in diagnosing this issue, here's the debug information gathered:

  • Streamlit version: 1.50.0
  • Python version: 3.14.2
  • Operating System: MacOs 26.1
  • Browser: Chrome

This information provides a specific context for when and where the issue is being observed. It's crucial for developers to pinpoint the exact versions and environments where such bugs manifest, allowing for more targeted testing and fixes. While no additional specific information was provided regarding the exact nature of the kwargs handling, this version information is a solid starting point for anyone looking into the st.plotly_chart component's internals.

Moving Forward

It's clear that this kwargs deprecation warning, when triggered by documented parameters in st.plotly_chart, is an inconvenient bug and a regression. The Streamlit team is aware of this and is likely working towards a resolution. For now, while we await a fix, you can generally ignore the warning if you are confident you are using documented parameters correctly. However, it's always a good practice to keep your Streamlit version updated to benefit from the latest bug fixes and improvements. If you're encountering this, checking the latest Streamlit release notes or GitHub issues can provide updates on the status of this particular problem.

For more information on Streamlit and its components, you can always refer to the official documentation:

Let's keep building awesome apps!