Fixing The Plotly Chart Kwargs Deprecation Warning In Streamlit

Hey there, fellow Streamlit enthusiasts! Have you ever been happily coding away, crafting beautiful interactive charts with Plotly, only to be greeted by an unexpected deprecation warning from st.plotly_chart? Specifically, you might be seeing a warning about kwargs even when you're sure you haven't passed any extra, undocumented keyword arguments. This can be a bit puzzling, especially when you're only using parameters that are clearly outlined in the official documentation. In this article, we're going to dive deep into this specific Streamlit plotly_chart kwargs deprecation warning, understand why it's happening, and most importantly, how to navigate it effectively. We'll explore the code example that triggers this warning and discuss the expected versus current behavior, giving you the clarity you need to keep your Streamlit applications running smoothly.

Understanding the plotly_chart kwargs Deprecation Warning

Let's get right into it. The core of the issue lies in how Streamlit handles arguments passed to its st.plotly_chart function. When you use st.plotly_chart(fig, width="content"), you're trying to let Streamlit intelligently manage the width of your Plotly chart based on the container it's placed in. This is a super handy feature, allowing your visualizations to be responsive and look great on different screen sizes without you having to manually set pixel values. However, recent changes in Streamlit's internal workings have introduced a warning that pops up specifically when variable keyword arguments (**kwargs) are detected. The warning message generally looks something 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." This message is quite clear about its intent: Streamlit is steering users away from using arbitrary kwargs for configuration and encouraging the use of a dedicated config parameter for Plotly-specific settings. The tricky part is that this warning seems to be triggered even when you're using documented parameters like width or height, which are not technically kwargs in the sense of being arbitrary or undocumented. This implies that the internal logic checking for kwargs might be a bit too enthusiastic, flagging parameters that are actually part of the function's intended interface.

This behavior can be particularly confusing because the documentation for st.plotly_chart often suggests using arguments like width and height for controlling the dimensions of the chart. When these standard arguments trigger a deprecation warning related to kwargs, it creates a disconnect between what the documentation implies and what the code actually produces. It's important to remember that deprecation warnings are there to guide developers towards more stable and future-proof APIs. In this case, the warning is signaling a shift in how chart configurations, including dimensions, might be handled in the future. While the current implementation might still work, it's a sign that the underlying system is evolving. The goal is to ensure that your Streamlit applications remain compatible and benefit from future updates without breaking. Understanding the nuances of this warning is key to writing cleaner, more maintainable Streamlit code. It encourages a more structured approach to passing configuration options, which ultimately benefits both the developer and the end-user by ensuring a more robust and predictable experience. So, while it might seem like a minor glitch, it's an important signal from the Streamlit developers about best practices moving forward.

Reproducible Code and the Unexpected Warning

To truly grasp the situation, let's look at the code example provided. It's a concise demonstration that clearly illustrates the problem. Here's the code in question:

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")

In this snippet, we first create a basic Plotly figure using plotly.graph_objects. We add a Barpolar trace and then set the figure's layout dimensions using update_layout. The crucial line is st.plotly_chart(fig, width="content"). Here, we're passing our Plotly figure (fig) and explicitly setting the width parameter to the string value `