lyst / lyst/lightfm

Model input: CSR vs COO sparse matrices ? (Different results)

Open
#555 1 comment 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Dominant language
Python
Stars
5.1k
Forks
724
PR merge metrics
No merged PRs in 30d

Description

I noticed a strange issue using the library with the sparse matrices format.

If I use the same interaction matrix but as CSR while training, I get different results when evaluating compared to using a COO matrix for interactions.
Is it a normal behavior ?

Also how can I be certain of the format I should use for all LighFM input:
lightfm.Dataset returns all COO matrices when building interactions and features, but in the source it's said that user_features and item_features should be as CSR.

Thanks for you help !

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the reported comparison using the same interaction matrix in CSR and COO formats, then compare the training and evaluation results. Check how LightFM handles the formats returned by lightfm.Dataset and determine whether the differing results indicate a bug or need clarification in the input-format guidance.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
machine-learning
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.