Lightning-AI/pytorch-lightning

Support all iterator modes for fit/validate/test/predict

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#16,830 opened on Feb 21, 2023

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Description

Description & Motivation

trainer.fit only works with CombinedLoader(..., mode="max_size_cycle"|"min_size")

trainer.{validate,test,predict} only works with CombinedLoader(..., mode="sequential")

This constraint is checked in the top-level loops: https://github.com/Lightning-AI/lightning/blob/0009cde1db1a9ab4e2f1e0a9f69a4affb59d5134/src/lightning/pytorch/loops/fit_loop.py#L351-L354 https://github.com/Lightning-AI/lightning/blob/0009cde1db1a9ab4e2f1e0a9f69a4affb59d5134/src/lightning/pytorch/loops/evaluation_loop.py#L182-L183

Pitch

Have all trainer functions support all modes

TODO:

  • FitLoop
  • EvaluationLoop (#17163)
  • PredictionLoop

Alternatives

Not do it

Additional context

This builds on top of https://github.com/Lightning-AI/lightning/pull/16726

cc @borda @justusschock @awaelchli

Contributor guide

Research direction
Inspect the fit loop and evaluation loop code links provided in the issue, understand how CombinedLoader modes are restricted, and extend support to all modes for fit and predict loops.
Tech stack
python
Domain
backendmachine learning
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
PythonPyTorch Lightning basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40