👀 Views: 16 💬 Answers: 1 📅 Created: 2025-06-13

python sorting comparison Python

I'm working through a tutorial and Quick question that's been bugging me - I'm facing a perplexing issue with sorting a list of dictionaries in Python 3.10 using a custom comparator... I expected the sorting to work based on a specific key, but I noticed inconsistent results. Here's what I have: ```python items = [ {'name': 'apple', 'quantity': 5}, {'name': 'banana', 'quantity': 1}, {'name': 'cherry', 'quantity': 3}, {'name': 'banana', 'quantity': 2}, ] # Custom comparator function def compare_items(item): return (item['name'], item['quantity']) sorted_items = sorted(items, key=compare_items) print(sorted_items) ``` When I run this code, I expect the output to be sorted primarily by the 'name' key and secondarily by the 'quantity' key. However, the result is: ``` [ {'name': 'apple', 'quantity': 5}, {'name': 'banana', 'quantity': 1}, {'name': 'banana', 'quantity': 2}, {'name': 'cherry', 'quantity': 3}, ] ``` The issue seems to be with how the sorting behaves for items with the same name. I initially thought it would sort the 'quantity' correctly for the two 'banana' entries, but it appears to prioritize the order they initially appeared in. This behavior contradicts my expectations based on the documentation of the `sorted()` function. I've also tried using the `operator.itemgetter` to see if that would yield a different result, but it also leads to the same issue. Here's the code: ```python from operator import itemgetter sorted_items = sorted(items, key=itemgetter('name', 'quantity')) ``` I was wondering if anyone could shed light on why this is happening and how I might achieve the desired sorting order. Is there a misstep in my approach, or is this a quirk of how Python handles sorting with tuples in dictionaries? Any insights would be greatly appreciated! I'm working on a API that needs to handle this. Is there a better approach? I'd really appreciate any guidance on this. This is for a CLI tool running on Debian.