SettingWithCopyWarning is one of the most common hurdles people run into when learning pandas. A quick web search will reveal scores of Stack Overflow questions, GitHub issues and forum posts from programmers trying to wrap their heads around what this warning means in their particular situation. It’s no surprise that many struggle with this; there are so many ways to index pandas data structures, each with its own particular nuance, and even pandas itself does not guarantee one single outcome for two lines of code that may look identical.
This guide explains why the warning is generated and shows you how to solve it. It also includes under-the-hood details to give you a better understanding of what’s happening and provides some history on the topic, giving you perspective on why it all works this way.
In order to explore
SettingWithCopyWarning, we’re going to use a data set of the prices of Xboxes sold in 3-day auctions on eBay from the book Modelling Online Auctions. Let’s take a look: