Is your feature request related to a problem? Please describe.
Currently, users must set output_transform = lambda output: output["pred"], output["label"] for metrics.
We have received much feedback from users that the lambda function is hard to understand.
Thanks for the discussion with @vfdev-5 in ignite ticket:
pytorch/ignite#2055 (comment)
I will try to add utility to simplify the usage of the metrics with the dictionary.