func (g *GradHelper) subBatches(s sgd.SampleSet) <-chan sgd.SampleSet {
batchSize := g.batchSize()
res := make(chan sgd.SampleSet, s.Len()/batchSize+1)
for i := 0; i < s.Len(); i += batchSize {
bs := batchSize
if bs > s.Len()-i {
bs = s.Len() - i
}
res <- s.Subset(i, i+bs)
}
close(res)
return res
}
