Search for a command to run...
An approach to counting items from a list of unknown items.
I am an AWS Certified Solutions Architect with over 12+ years of experience with a primary focus on AWS serverless solutions, AWS CDK, event driven architecture and Python.
No comments yet. Be the first to comment.
Fix error 1227 (42000): Access denied; you need (at least one of) the SUPER or SYSTEM_VARIABLES_ADMIN privilege(s) for this operation
How to resolve the error: Invalid stage identifier specified (Service: ApiGateway, Status Code: 400)
A walkthrough for a .NETCore serverless project
A beginner's guide
Easily adopt best practices such as tracing, structured logging, custom metrics, and more.
Python is a "batteries included" language, meaning it comes with a large library of useful modules. One such library is "itertools" which offer multiple functions with various use cases. In this post, we will look into one of its functions: unique_everseen
unique_everseen() is part of more_itertools library. The library can be installed via:
pip install more-itertools
unique_everseen(iterable), takes an iterable parameter and yield unique elements, preserving order.
>>> list(unique_everseen('AAAABBBCCDAABBB'))
['A', 'B', 'C', 'D']
One of the practical usages can be to perform activities like stock count or to prep data for reporting purposes.
In the below example, we have a list of products, assume we have no knowledge of the type or count of items in the list.
from more_itertools import unique_everseen
data = ['Product A', 'Product B', 'Product A', 'Product E', 'Product B', 'Product F', 'Product N', 'Product B',
'Product N', 'Product A', 'Product B', 'Product A']
final_count = {k:data.count(k) for k in unique_everseen(data)}
print(f'We have {len(final_count)} products. The count of each product is as below:\n{final_count}')
The above code will print, the product name as dict key and its count as value:
We have 5 products. The count of each product is as below:
{'Product A': 4, 'Product B': 4, 'Product E': 1, 'Product F': 1, 'Product N': 2}
This approach seems simpler and faster than using loops. Remember that list objects are unhashable - you can use the key parameter to transform the list to a tuple (which is hashable) to further improve the performance.
final_count = {k:data.count(k) for k in unique_everseen(data, key=tuple)}
I hope you've found this article useful. Follow me if you are interested in:
Python
AWS Architecture & Security.
AWS Serverless solutions.