Streamlit: Plotly_chart Kwargs Deprecation Warning Fix

by Alex Johnson 55 views

Hey there, data visualization enthusiasts! If you've been working with Streamlit and its fantastic integration with Plotly, you might have encountered a rather pesky warning lately. It pops up when you're trying to set the width or height of your charts using parameters like width="content". The warning message mentions something about kwargs being deprecated. Now, for those of you who aren't deep into the nitty-gritty of Python's inner workings, this can be a bit confusing, especially when you're just trying to make your charts look good and aren't explicitly passing any variable keyword arguments yourself. We're here to clear the air, explain why this is happening, and how you can navigate it like a pro.

Understanding the st.plotly_chart Function and kwargs

Let's dive into what's actually going on under the hood with st.plotly_chart. This Streamlit function is your gateway to embedding interactive Plotly charts directly into your web applications. It's designed to be user-friendly, allowing you to pass your Plotly figure object and then customize its appearance within the Streamlit context. One of the ways you can customize it is by controlling the dimensions of the displayed chart. Previously, and in a way that's now flagged as a potential issue, Streamlit allowed you to pass a variety of keyword arguments (kwargs) directly to st.plotly_chart to control aspects like width and height. These kwargs would then be passed down to the underlying Plotly rendering mechanisms.

However, as libraries evolve, so do their best practices. The Streamlit team has been working on refining how parameters are handled to make the API cleaner and more predictable. The core of the issue lies in how Streamlit differentiates between explicitly documented parameters and those passed through a more flexible, but potentially less controlled, kwargs mechanism. When you use arguments like width="content", which is a documented and intended way to control the chart's width to fit its container, Streamlit's internal checks might be flagging this as a usage of kwargs that could lead to conflicts or unexpected behavior in the future. It's not that you're doing anything wrong per se, but rather that the way you're interacting with the function is triggering a warning about a broader system change.

The warning itself, "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," is a heads-up. It's telling you that relying on passing arbitrary keyword arguments directly to st.plotly_chart might not be the way forward. Instead, Streamlit is guiding you towards using the dedicated config argument, which is specifically designed to pass configuration options to the underlying charting library (in this case, Plotly).

This is a common pattern in software development: as features mature, developers often introduce more structured ways of handling options to improve maintainability and prevent errors. For instance, instead of passing many individual arguments that could potentially clash or be misspelled, a config object (often a dictionary) provides a centralized place for all such settings. This makes the API cleaner and the developer experience smoother in the long run. So, while the warning might seem a bit alarming at first, it's actually a sign of Streamlit actively improving its codebase and guiding users towards a more robust and future-proof way of building applications. It's all about making your Streamlit apps more stable and easier to manage as they grow.

Reproducing the Warning: A Simple Example

To make sure we're all on the same page, let's look at a straightforward code example that triggers this warning. It's surprisingly simple, which highlights why it might catch developers off guard.

import plotly.graph_objects as go
import streamlit as st

# Create a basic Plotly figure
fig = go.Figure()
fig.add_trace(go.Barpolar(r=[1], theta=[0], width=[120]))
fig.update_layout(width=500, height=360)

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

In this snippet, we're doing a few things:

  1. Importing Libraries: We import plotly.graph_objects as go for creating our figure and streamlit as st for our web app.
  2. Creating a Plotly Figure: We initialize a go.Figure() and add a simple Barpolar trace to it. This is just to have a valid Plotly figure to display.
  3. Setting Layout Dimensions (Optional but illustrative): fig.update_layout(width=500, height=360) sets some initial dimensions for the figure itself. While these are set here, they might be overridden or influenced by the Streamlit display parameters.
  4. Displaying with st.plotly_chart: The crucial line is st.plotly_chart(fig, width="content"). Here, we're passing our fig object and explicitly setting the width parameter to the string value `