EpochOutputStore can optionally store the data to the state

🚀 Feature

The idea is to give an option to have the following:

eos = EpochOutputStore()

evaluator = create_supervised_evaluator(model, metrics)
eos.attach(evaluator, name="eval_data")

# Adding the name is equivalent to
# name = "eval_data"
# @evaluator.on(Events.EPOCH_COMPLETED, name)
# def store_data(engine, name):
#     setattr(engine.state, name, eos.data)

state = evaluator.run(data)
print(len(state.eval_data))

In addition, it would make sense to move it from contrib to core as well, keeping BC.

[radekosmulski]

I opened #1974 but it is probably quite basic, happy to implement any changes that might be needed 🙂

This is only a draft - as a next step, will move it out of contrib keeping BC.

[radekosmulski]

@vfdev-5 - would love to! Will read through the code today and either come here to ask questions if anything is unclear or will start working on a draft of the implementation 🙂