// Matrix factorization.
func mfFunc(idx uint64, ctx *occult.Context) (occult.Value, error) {
opt := ctx.Options.(*Options)
// input 0 has chunks of data
chunks := ctx.Inputs()[0] // chunks of observations
// input 1 has aggregated data from a previous pass through the entire data set
in1, e1 := ctx.Inputs()[1](0) // aggregated data
if e1 != nil {
return nil, e1
}
cf := in1.(*CF)
cf.InitMF(opt.numFactors, opt.learnRate, opt.regularization, opt.meanNorm)
// Now we can iterate over chunks and for each chunk.
var c, iter uint64
for ; iter < idx; iter++ {
glog.V(1).Infof("GD iter: %d", iter)
for c = 0; ; c++ {
in0, err := chunks(c)
if err == occult.ErrEndOfArray {
break
}
s := in0.([]Obs)
for _, v := range s {
cf.GDUpdate(v.User, v.Item, v.Rating)
}
}
}
return cf, nil
}
// Aggregate CF.
func aggCFFunc(idx uint64, ctx *occult.Context) (occult.Value, error) {
opt := ctx.Options.(*Options)
if idx > 0 {
return nil, occult.ErrEndOfArray
}
cf := NewCF(opt.alpha)
ch := ctx.Inputs()[0].MapAll(0, ctx)
for {
v, ok := <-ch
if !ok {
if glog.V(5) {
glog.Infof("aggCFFunc returning idx:%d, NumRatingsx:%#v", idx, cf.NumRatings)
}
return cf, nil
}
q := v.(*CF)
cf.Reduce(q)
}
}
// Computes various global statistics on the data set.
func cfFunc(idx uint64, ctx *occult.Context) (occult.Value, error) {
opt := ctx.Options.(*Options)
in, err := ctx.Inputs()[0](idx)
if err != nil && err != occult.ErrEndOfArray {
return nil, err // something is wrong
}
if in == nil {
return nil, occult.ErrEndOfArray
}
s := in.([]Obs)
cf := NewCF(opt.alpha)
for _, v := range s {
r := v.Rating
if r < 1 || r > 5 {
return nil, fmt.Errorf("rating out of range: %d", r)
}
cf.Update(v.User, v.Item, v.Rating)
}
if glog.V(5) {
glog.Infof("cfFunc returning idx:%d, NumRatingsx:%#v", idx, cf.NumRatings)
}
return cf, err // err may be ErrEndOfArray
}