One of the reasons I like using pandas instead of Excel for data analysis is that it is easier to avoid certain types of copy-paste Excel errors. As great as pandas is, there is still plenty of opportunity to make errors with pandas code. This article discusses a subtle issue with pandas groupby code that can lead to big errors if you’re not careful. I’m writing this because I have happened upon this in the past but it still bit me big time just recently. I hope this article can help a fe...
