Solving Streamlit's `st.plotly_chart` `kwargs` Deprecation Warning

Streamlit developers might have recently noticed a rather persistent kwargs deprecation warning when using st.plotly_chart, especially when trying to set the chart's width or height with options like width="content". This warning can be a bit confusing because, on the surface, you might feel like you're just using documented parameters and not explicitly passing any "variable keyword arguments" (the **kwargs part of a function signature). Fear not! You're not alone in encountering this, and it's a common point of confusion that we're going to clear up today. The core of the issue lies in how Streamlit’s st.plotly_chart function handles certain parameters that were previously passed implicitly through **kwargs but are now being moved to more explicit arguments or a dedicated config dictionary. Specifically, parameters like width="content" or height were previously processed in a way that sometimes triggered this kwargs mechanism behind the scenes, even if you weren't thinking of them as **kwargs yourselves. The deprecation warning itself is a heads-up from the Streamlit team, letting us know that this implicit handling will change in future releases. It's designed to guide us toward a more robust and maintainable way of customizing our Plotly charts within Streamlit applications. The message often states: "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 can be particularly frustrating when you're just trying to make your chart fit nicely using width="content" and suddenly a warning pops up, making you wonder if you've done something wrong. The good news is that this isn't a bug in your code, but rather a transitional phase in Streamlit's API evolution. Understanding why this warning appears is the first step toward resolving it and ensuring your applications are ready for future Streamlit updates. This change is ultimately for the betterment of the ecosystem, promoting clearer code and more predictable behavior. It encourages developers to be more intentional about how they configure their visualizations, especially when dealing with the powerful and flexible Plotly library. So, let's dive deeper into what kwargs means in this context and how we can adapt our code to embrace these new, clearer guidelines, making our Streamlit apps even more polished and warning-free.

Understanding the st.plotly_chart Deprecation Warning

The st.plotly_chart kwargs deprecation warning that many Streamlit users are encountering, especially when attempting to set chart dimensions with width="content", can be quite perplexing at first. It pops up, seemingly out of nowhere, even when you feel you're following the documentation to the letter. This warning is Streamlit's way of signaling a change in how it expects to receive certain configuration parameters for Plotly charts. In the world of Python, **kwargs is a powerful tool that allows functions to accept an arbitrary number of keyword arguments, collecting them into a dictionary. Historically, st.plotly_chart leveraged this flexibility to pass various parameters directly to the underlying Plotly rendering mechanism or to handle some of its own internal options. This made the function versatile but sometimes less explicit. When you specify width="content", for instance, you're trying to make your Plotly chart fill the width of its container in your Streamlit application. While this is a perfectly valid and desirable behavior, the way st.plotly_chart might have internally processed width="content" could have, in certain versions or specific scenarios, routed it through the generic kwargs pathway. This internal handling, though invisible to the end user, is what the deprecation warning is now targeting. The warning is not about width="content" being an invalid setting; rather, it's about the method Streamlit uses to process it behind the scenes transitioning to a more explicit model. The core message