Galaxy | Tool Preview

VAPOR (version 1.0.2+galaxy3)
Select a multisample fasta dataset with reference sequences to base classification on.
Specify the sequenced reads dataset.
Determines the maximum number of candidate matches sorted by score that will be reported. Set to zero to get all candidate matches reported.
Optional arguments
Optional arguments 0

What it does

VAPOR is a tool for classification of Influenza samples from raw short read sequence data for downstream bioinformatics analysis. VAPOR works on a fasta file of full-length reference sequences for a given genome segment and a set of sequenced reads, and attempts to retrieve the reference that is closest to the sequenced strain.

sub_sample is not an option here (compared to the tool on GitHub), since you can always build a workflow that preprocesses your reads to a (random) subsample. You can use this output as your reads file for VAPOR.